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    Anisotropic nanocomposite soft/hard multilayer magnets
    Wei Liu(刘伟), Zhidong Zhang(张志东)
    Chin. Phys. B, 2017, 26 (11): 117502.   DOI: 10.1088/1674-1056/26/11/117502
    Abstract602)   HTML    PDF (13755KB)(459)      

    Experimental and theoretical researches on nanostructured exchange coupled magnets have been carried out since about 1988.Here,we review the structure and magnetic properties of the anisotropic nanocomposite soft/hard multilayer magnets including some new results and phenomena from an experimental point of view.According to the different component of the oriented hard phase in the nanocomposite soft/hard multilayer magnets,three types of magnets will be discussed:1) anisotropic Nd2Fe14B based nanocomposite multilayer magnets,2) anisotropic SmCo5 based nanocomposite multilayer magnets,and 3) anisotropic rare-earth free based nanocomposite multilayer magnets.For each of them,the formation of the oriented hard phase,exchange coupling,coercivity mechanism,and magnetic properties of the corresponding anisotropic nanocomposite multilayer magnets are briefly reviewed,and then the prospect of realization of bulk magnets on new results of anisotropic nanocomposite multilayer magnets will be carried out.

    Exchange couplings in magnetic films
    Liu Wei (刘伟), Liu Xiong-Hua (刘雄华), Cui Wei-Bin (崔伟斌), Gong Wen-Jie (龚文杰), Zhang Zhi-Dong (张志东)
    Chin. Phys. B, 2013, 22 (2): 027104.   DOI: 10.1088/1674-1056/22/2/027104
    Abstract1117)      PDF (2456KB)(2155)      
    Recent advances in the study of exchange couplings in magnetic films are introduced. To provide a comprehensive understanding of exchange coupling, we have designed different bilayers, trilayers and multilayers, such as anisotropic hard- /soft-magnetic multilayer films, ferromagnetic/antiferromagnetic/ferromagnetic trilayers, [Pt/Co]/NiFe/NiO heterostructures, Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide (AAO) template. The exchange-coupling interaction between soft- and hard-magnetic phases, interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer, ferromagnetic layer, and antiferromagnetic layer. Some particular physical phenomena have been observed and explained.
    Structural changes concurrent with ferromagnetic transition
    Yang Sen (杨森), Bao Hui-Xin (鲍慧新), Zhou Chao (周超), Wang Yu (王宇), Ren Xiao-Bing (任晓兵), Song Xiao-Ping (宋晓平), Yoshitaka Matsushita, Yoshio Katsuya, Masahiko Tanaka, Keisuke Kobayashi
    Chin. Phys. B, 2013, 22 (4): 046101.   DOI: 10.1088/1674-1056/22/4/046101
    Abstract844)      PDF (1350KB)(1511)      

    Ferromagnetic transition has generally been considered to involve only an ordering of magnetic moment with no change in the host crystal structure or symmetry, as evidenced by a wealth of crystal structure data from conventional X-ray diffractometry (XRD). However, the existence of magnetostriction in all known ferromagnetic systems indicates that the magnetic moment is coupled to the crystal lattice; hence there is a possibility that magnetic ordering may cause a change in crystal structure. With the development of high-resolution synchrotron XRD, more and more magnetic transitions have been found to be accompanied by simultaneous structural changes. In this article, we review our recent progress in understanding the structural change at a ferromagnetic transition, including synchrotron XRD evidence of structural changes at the ferromagnetic transition, a phenomenological theory of crystal structure changes accompanying ferromagnetic transitions, new insight into magnetic morphotropic phase boundaries (MPB) and so on. Two intriguing implications of non-centric symmetry in the ferromagnetic phase and the first-order nature of ferromagnetic transition are also discussed here. In short, this review is intended to give a self-consistent and logical account of structural change occurring simultaneously with a ferromagnetic transition, which may provide new insight for developing highly magneto-responsive materials.

    Manipulating magnetic anisotropy and ultrafast spin dynamics of magnetic nanostructures
    Cheng Zhao-Hua (成昭华), He Wei (何为), Zhang Xiang-Qun (张向群), Sun Da-Li (孙达力), Du Hai-Feng (杜海峰), Wu Qiong (吴琼), Ye Jun (叶军), Fang Ya-Peng (房亚鹏), Liu Hao-Liang (刘郝亮)
    Chin. Phys. B, 2015, 24 (7): 077505.   DOI: 10.1088/1674-1056/24/7/077505
    Abstract835)   HTML    PDF (3669KB)(972)      

    We present our extensive research into magnetic anisotropy. We tuned the terrace width of Si(111) substrate by a novel method: varying the direction of heating current and consequently manipulating the magnetic anisotropy of magnetic structures on the stepped substrate by decorating its atomic steps. Laser-induced ultrafast demagnetization of a CoFeB/MgO/CoFeB magnetic tunneling junction was explored by the time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electron tunneling current. This opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions. Furthermore, an all-optical TR-MOKE technique provides the flexibility for exploring the nonlinear magnetization dynamics in ferromagnetic materials, especially with metallic materials.

    Magnetic properties and magnetocaloric effects in NaZn13-type La(Fe, Al)13-based compounds
    Shen Bao-Gen (沈保根), Hu Feng-Xia (胡凤霞), Dong Qiao-Yan (董巧燕), Sun Ji-Rong (孙继荣)
    Chin. Phys. B, 2013, 22 (1): 017502.   DOI: 10.1088/1674-1056/22/1/017502
    Abstract1034)      PDF (713KB)(1018)      
    In this article, our recent progress concerning the effects of atomic substitution, magnetic field, and temperature on the magnetic and magnetocaloric properties of the LaFe13-xAlx compounds are reviewed. With an increase of the aluminum content, the compounds exhibit successively an antiferromagnetic (AFM) state, a ferromagnetic (FM) state, and a mictomagnetic state. Furthermore, the AFM coupling of LaFe13-xAlx can be converted to an FM one by substituting Si for Al, Co for Fe, and magnetic rare-earth R for La, or introducing interstitial C or H atoms. However, low doping levels lead to FM clusters embedded in an AFM matrix, and the resultant compounds can undergo, under appropriate applied fields, first an AFM-FM and then an FM-AFM phase transition while heated, with significant magnetic relaxation in the vicinity of the transition temperature. The Curie temperature of LaFe13-xAlx can be shifted to room temperature by choosing appropriate contents of Co, C, or H, and a strong magnetocaloric effect can be obtained around the transition temperature. For example, for the LaFe11.5Al1.5C0.2H1.0 compound, the maximal entropy change reaches 13.8 J·kg-1·K-1 for a field change of 0-5 T, occurring around room temperature. It is 42% higher than that of Gd, and therefore, this compound is a promising room-temperature magnetic refrigerant.
    Emergent phenomena in manganites under spatial confinement
    Shen Jian (沈健), T. Z. Ward, L. F. Yin
    Chin. Phys. B, 2013, 22 (1): 017501.   DOI: 10.1088/1674-1056/22/1/017501
    Abstract1196)      PDF (2047KB)(1368)      
    It is becoming increasingly clear that the exotic properties displayed by correlated electronic materials such as high- Tc superconductivity in cuprates, colossal magnetoresistance (CMR) in manganites, and heavy-fermion compounds are intimately related to the coexistence of competing nearly degenerate states which couple simultaneously active degrees of freedom–charge, lattice, orbital, and spin states. The striking phenomena associated with these materials are due in a large part to spatial electronic inhomogeneities, or electronic phase separation (EPS). In many of these hard materials, the functionality is a result of the soft electronic component that leads to self-organization.
    In this paper, we review our recent work on a novel spatial confinement technique that has led to some fascinating new discoveries about the role of EPS in manganites. Using lithographic techniques to confine manganite thin films to length scales of the EPS domains that reside within them, it is possible to simultaneously probe EPS domains with different electronic states. This method allows for a much more complete view of the phases residing in a material and gives vital information on phase formation, movement, and fluctuation.
    Pushing this trend to its limit, we propose to control the formation process of the EPS using external local fields, which include magnetic exchange field, strain field, and electric field. We term the ability to pattern EPS “electronic nanofabrication.” This method allows us to control the global physical properties of the system at a very fundamental level, and greatly enhances the potential for realizing true oxide electronics.
    Magnetic nanoparticle-based cancer therapy
    Yu Jing (余靓), Huang Dong-Yan (黄冬雁), Muhammad Zubair Yousaf, Hou Yang-Long (侯仰龙), Gao Song (高松)
    Chin. Phys. B, 2013, 22 (2): 027506.   DOI: 10.1088/1674-1056/22/2/027506
    Abstract894)      PDF (1586KB)(2132)      
    Nanoparticles (NPs) with easily modified surfaces have been playing an important role in biomedicine. As cancer is one of the major causes of death, tremendous efforts have been devoted to advance the methods of cancer diagnosis and therapy. Recently, magnetic nanoparticles (MNPs) that are responsive to a magnetic field have shown great promise in cancer therapy. Compared with traditional cancer therapy, magnetic field triggered therapeutic approaches can treat cancer in an unconventional but more effective and safer way. In this review, we will discuss the recent progress in cancer therapies based on MNPs, mainly including magnetic hyperthermia, magnetic specific targeting, magnetically controlled drug delivery, magnetofection, and magnetic switches for controlling cell fate. Some recently developed strategies such as magnetic resonance imaging (MRI) monitoring cancer therapy and magnetic tissue engineering are also addressed.
    Resistance switching in oxides with inhomogeneous conductivity
    Shang Da-Shang (尚大山), Sun Ji-Rong (孙继荣), Shen Bao-Gen (沈保根), Wuttig Matthias
    Chin. Phys. B, 2013, 22 (6): 067202.   DOI: 10.1088/1674-1056/22/6/067202
    Abstract802)      PDF (4383KB)(1390)      
    Electric-field-induced resistance switching (RS) phenomena have been studied for over 60 years in metal/dielectrics/metal structures. In these experiments a wide range of dielectrics have been studied including binary transition metal oxides, perovskite oxides, chalcogenides, carbon- and silicon-based materials, as well as organic materials. RS phenomena can be used to store information and offer an attractive performance, which encompasses fast switching speeds, high scalability, and the desirable compatibility with Si-based complementary metal-oxide-semiconductor fabrication. This is promising for nonvolatile memory technology, i.e. resistance random access memory (RRAM). However, a comprehensive understanding of the underlying mechanism is still lacking. This impedes a faster product development as well as an accurate assessment of the device performance potential. Generally speaking, RS occurs not in the entire dielectric but only in a small, confined region, which results from the local variation of conductivity in dielectrics. In this review, we focus on the RS in oxides with such an inhomogeneous conductivity. According to the origin of the conductivity inhomogeneity, the RS phenomena and their working mechanism are reviewed by dividing them into two aspects: interface RS, based on the change of contact resistance at metal/oxide interface due to the change of Schottky barrier and interface chemical layer, and bulk RS, realized by the formation, connection, and disconnection of conductive channels in the oxides. Finally the current challenges of RS investigation and the potential improvement of the RS performance for the nonvolatile memories are discussed.
    Mn-based antiperovskite functional materials: Review of research
    Tong Peng (童鹏), Wang Bo-Sen (王铂森), Sun Yu-Ping (孙玉平)
    Chin. Phys. B, 2013, 22 (6): 067501.   DOI: 10.1088/1674-1056/22/6/067501
    Abstract1205)      PDF (2004KB)(1467)      
    Our recent research on the Mn-based antiperovskite functional materials AXMn3 (A: metal or semiconducting elements; X: C or N) is outlined. Antiperovskite carbides (e.g., AlCMn3) show large magnetocaloric effect comparable to those of typical magnetic refrigerant materials. Enhanced giant magnetoresistance up to 70% at 50 kOe (1 Oe = 79.5775 A·m-1) over a wide temperature span was obtained in Ga1-xZnxCMn3 and GaCMn3-xNix. In Cu0.3Sn0.5NMn3.2, negative thermal expansion (NTE) was achieved in a wide temperature region covering room temperature (α = -6.8 ppm/K, 150 K-400 K). Neutron pair distribution function analysis suggests the Cu/Sn-Mn bond fluctuation is the driving force for the NTE in Cu1-xSnxNMn3. In CuN1-xCxMn3 and CuNMn3-yCoy, the temperature coefficient of resistivity (TCR) decreases monotonically from positive to negative as Co or C content increases. TCR is extremely low when the composition approaches the critical points. For example, TCR is ~ 1.29 ppm/K between 240 K and 320 K in CuN0.95C0.05Mn3, which is one twentieth of that in the typical low-TCR materials (~ 25 ppm/K). By studying the critical scaling behavior and X deficiency effect, some clues of localized-electron magnetism have been found against the background of electronic itinerant magnetism.
    Magnetic nanoparticle-based cancer nanodiagnostics
    Muhammad Zubair Yousaf, Yu Jing (余靓), Hou Yang-Long (侯仰龙), Gao Song (高松)
    Chin. Phys. B, 2013, 22 (5): 058702.   DOI: 10.1088/1674-1056/22/5/058702
    Abstract762)      PDF (4052KB)(2257)      
    Diagnosis facilitates the discovery of an impending disease. A complete and accurate treatment of cancer depends heavily on its early medical diagnosis. Cancer, one of the most fatal diseases world-wide, consistently affects a larger number of patients each year. Magnetism, a physical property arising from the motion of electrical charges, which causes attraction and repulsion between objects and does not involve radiation, has been under intense investigation for several years. Magnetic materials show great promise in the application of image contrast enhancement to accurately image and diagnose cancer. Chelating gadolinium (Gd III) and magnetic nanoparticles (MNPs) have the prospect to pave the way for diagnosis, operative management, and adjuvant therapy of different kinds of cancers. The potential of MNP-based magnetic resonance (MR) contrast agents (CAs) now makes it possible to image portions of a tumor in parts of the body that would be unclear with the conventional magnetic resonance imaging (MRI). Multiple functionalities like variety of targeting ligands and image contrast enhancement have recently been added to the MNPs. Keeping aside the additional complexities in synthetic steps, costs, more convoluted behavior, and effects in-vivo, multifunctional MNPs still face great regulatory hurdles before clinical availability for cancer patients. The trade-off between additional functionality and complexity is a subject of ongoing debate. The recent progress regarding the types, design, synthesis, morphology, characterization, modification, and the in-vivo and in-vitro uses of different MRI contrast agents, including MNPs, to diagnose cancer will be the focus of this review. As our knowledge of MNPs’ characteristics and applications expands, their role in the future management of cancer patients will become very important. Current hurdles are also discussed, along with future prospects of MNPs as the savior of cancer victims.
    Reactively sputtered Fe3O4-based films for spintronics
    Li Peng (李鹏), Jin Chao (金朝), Mi Wen-Bo (米文博), Bai Hai-Li (白海力)
    Chin. Phys. B, 2013, 22 (4): 047505.   DOI: 10.1088/1674-1056/22/4/047505
    Abstract626)      PDF (2911KB)(1520)      
    Half metallic polycrystalline, epitaxial Fe3O4 films and Fe3O4-based heterostructures for spintronics were fabricated by DC reactive magnetron sputtering. Large tunneling magnetoresistance was found in the polycrystalline Fe3O4 films and attributed to the insulating grain boundaries. The pinning effect of the moments at the grain boundaries leads to a significant exchange bias. Frozen interfacial/surface moments induce weak saturation of the high-field magnetoresistance. The films show a moment rotation related butterfly-shaped magnetoresistance. It was found that in the films, natural growth defects, antiphase boundaries, and magnetocrystalline anisotropy play important roles in high-order anisotropic magnetoresistance. Spin injection from Fe3O4 films to semiconductive Si and ZnO was measured to be 45% and 28.5%, respectively. The positive magnetoresistance in the Fe3O4-based heterostructures is considered to be caused by a shift of the Fe3O4 eg ↑ band near the interface. Enhanced magnetization was observed in Fe3O4/BiFeO3 heterostructures experimentally and further proved by first principle calculations. The enhanced magnetization can be explained by spin moments of the thin BiFeO3 layer substantially reversing into a ferromagnetic arrangement under a strong coupling that is principally induced by electronic orbital reconstruction at the interface.
    Phase transitions and magnetocaloric effects in intermetallic compounds MnFeX (X=P, As, Si, Ge)
    O. Tegus (特古斯), Bao Li-Hong (包黎红), Song Lin (松林)
    Chin. Phys. B, 2013, 22 (3): 037506.   DOI: 10.1088/1674-1056/22/3/037506
    Abstract1129)      PDF (688KB)(1181)      
    Since the discovery of giant magnetocaloric effect in MnFeP1-xAsx compounds, much valuable work has been performed to develop and improve Fe2P-type transition-metal-based magnetic refrigerants. In this article, the recent progress of our studies on fundamental aspects of theoretical considerations and experimental techniques, effects of atomic substitution on the magnetism and magnetocalorics of Fe2P-type intermetallic compounds MnFeX (X=P, As, Ge, Si) is reviewed. Substituting Si (or Ge) for As leads to an As-free new magnetic material MnFeP1-xSi(Ge)x. These new materials show large magnetocaloric effects resembling MnFe(P, As) near room temperature. Some new physical phenomena, such as huge thermal hysteresis and ‘virgin’ effect, were found in new materials. On the basis of Landau theory, a theoretical model was developed for studying the mechanism of phase transition in these materials. Our studies reveal that MnFe(P, Si) compound is a very promising material for room-temperature magnetic refrigeration and thermo-magnetic power generation.
    Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys
    Hu Feng-Xia(胡凤霞), Shen Bao-Gen (沈保根), Sun Ji-Rong(孙继荣)
    Chin. Phys. B, 2013, 22 (3): 037505.   DOI: 10.1088/1674-1056/22/3/037505
    Abstract1226)      PDF (1295KB)(1241)      
    Our recent progress on magnetic entropy change (ΔS) involving martensitic transition in both conventional and metamagnetic NiMn-based Heusler alloys is reviewed. For the conventional alloys, where both martensite and austenite exhibit ferromagnetic (FM) behavior but show differentmagnetic anisotropies, a positive ΔS as large as 4.1 J·kg-1·K-1 under a field change of 0–0.9 T was first observed at martensitic transition temperature TM ~ 197 K. Through adjusting the Ni:Mn:Ga ratio to affect valence electron concentration e/a, TM was successfully tuned to room temperature, and a large negative ΔS was observed in a single crystal. The -ΔS attained 18.0 J·kg-1·K-1 under a field change of 0–5 T. We also focused on the metamagnetic alloys that show mechanisms different from the conventional ones. It was found that post-annealing in suitable conditions or introducing interstitial H atoms can shift the TM across a wide temperature range while retaining the strong metamagnetic behavior, and hence, retaining large magnetocaloric effect (MCE) and magnetoresistance (MR). The melt-spun technique can disorder atoms and make the ribbons display a B2 structure, but the metamagnetic behavior, as well as the MCE, becomes weak due to the enhanced saturated magnetization of martensites. We also studied the effect of Fe/Co co-doping in Ni45(Co1-xFex)5Mn36.6In13.4 metamagnetic alloys. Introduction of Fe atoms can assist the conversion of the Mn–Mn coupling from antiferromagnetic to ferromagnetic, thus maintaining the strong metamagnetic behavior and large MCE and MR. Furthermore, a small thermal hysteresis but significant magnetic hysteresis was observed around TM in Ni51Mn49-xInx metamagnetic systems, which must be related to different nucleation mechanisms of structural transition under different external perturbations.
    Review of magnetocaloric effect in perovskite-type oxides
    Zhong Wei (钟伟), Au Chak-Tong (区泽棠), Du You-Wei (都有为)
    Chin. Phys. B, 2013, 22 (5): 057501.   DOI: 10.1088/1674-1056/22/5/057501
    Abstract1072)      PDF (1168KB)(2437)      
    We survey the magnetocaloric effect in perovskite-type oxides (including doped ABO3-type manganese oxides, A3B2O7-type two-layered perovskite oxides, and A2B'B''O6-type ordered double-perovskite oxides). Magnetic entropy changes larger than those of gadolinium can be observed in polycrystalline La1-xCaxMnO3 and alkali-metal (Na or K) doped La0.8Ca0.2MnO3 perovskite-type manganese oxides. The large magnetic entropy change produced by an abrupt reduction of magnetization is attributed to the anomalous thermal expansion at the Curie temperature. Considerable magnetic entropy changes can also be observed in two-layered perovskites La1.6Ca1.4Mn2O7 and La2.5-xK0.5+xMn2O7+δ (0 < x < 0.5), and double-perovskite Ba2Fe1+xMo1-xO6 (0 ≤ x ≤ 0.3) near their respective Curie temperatures. Compared with rare earth metals and their alloys, the perovskite-type oxides are lower in cost, and they exhibit higher chemical stability and higher electrical resistivity, which together favor lower eddy-current heating. They are potential magnetic refrigerants at high temperatures, especially near room temperature.
    High frequency magnetic properties of ferromagnetic thin films and magnetization dynamics of coherent precession
    Jiang Chang-Jun (蒋长军), Fan Xiao-Long (范小龙), Xue De-Sheng (薛德胜)
    Chin. Phys. B, 2015, 24 (5): 057504.   DOI: 10.1088/1674-1056/24/5/057504
    Abstract912)   HTML    PDF (2351KB)(1526)      
    We focus on the ferromagnetic thin films and review progress in understanding the magnetization dynamic of coherent precession, its application in seeking better high frequency magnetic properties for magnetic materials at GHz frequency, as well as new approaches to these materials' characterization. High frequency magnetic properties of magnetic materials determined by the magnetization dynamics of coherent precession are described by the Landau–Lifshitz–Gilbert equation. However, the complexity of the equation results in a lack of analytically universal information between the high frequency magnetic properties and the magnetization dynamics of coherent precession. Consequently, searching for magnetic materials with higher permeability at higher working frequency is still done case by case.
    Martensitic transformation & related magnetic effects in Ni-Mn-based ferro magnetic shape memory alloys
    Wang Dun-Hui (王敦辉), Han Zhi-Da (韩志达), Xuan Hai-Cheng (轩海成), Ma Sheng-Can (马胜灿), Chen Shui-Yuan (陈水源), Zhang Cheng-Liang (张成亮), Du You-Wei (都有为)
    Chin. Phys. B, 2013, 22 (7): 077506.   DOI: 10.1088/1674-1056/22/7/077506
    Abstract892)      PDF (772KB)(2035)      
    Ferromagnetic shape memory alloys, which undergo the martensitic transformation, are famous multifunctional materials. They exhibit many interesting magnetic properties around the martensitic transformation temperature due to the strong coupling between magnetism and structure. Tuning magnetic phase transition and optimizing the magnetic effects in these alloys are of great importance. In this paper, the regulation of martensitic transformation and the investigation of some related magnetic effects in Ni-Mn-based alloys are reviewed based on our recent research results.
    Progress in bulk MgCu2-type rare-earth iron magnetostrictive compounds
    Ren Wei-Jun (任卫军), Zhang Zhi-Dong (张志东)
    Chin. Phys. B, 2013, 22 (7): 077507.   DOI: 10.1088/1674-1056/22/7/077507
    Abstract569)      PDF (1077KB)(1604)      
    Studies of bulk MgCu2-type rare-earth iron compounds with Laves phase are reviewed. The relationship between magnetostriction and structural distortion and the consequent crystallographic method for measuring magnetostriction are introduced at first. Then we review recent progress in understanding bulk magnetostrictive Laves phase materials, especially the magnetostriction and the minimization of the anisotropy of the light rare-earth Pr-and Sm-based compounds. Finally, a summary and outlook for this kind of compounds are presented.
    High-mobility two-dimensional electron gases at oxide interfaces:Origin and opportunities
    Chen Yun-Zhong (陈允忠), Nini Pryds, Sun Ji-Rong (孙继荣), Shen Bao-Gen (沈保根), Søren Linderoth
    Chin. Phys. B, 2013, 22 (11): 116803.   DOI: 10.1088/1674-1056/22/11/116803
    Abstract708)      PDF (1772KB)(1458)      
    Our recent experimental work on metallic and insulating interfaces controlled by interfacial redox reactions in SrTiO3-based heterostructures is reviewed along with a more general background of two-dimensional electron gas (2DEG) at oxide interfaces. Due to the presence of oxygen vacancies at the SrTiO3 surface, metallic conduction can be created at room temperature in perovskite-type interfaces when the overlayer oxide ABO3 has Al, Ti, Zr, or Hf elements at the B sites. Furthermore, relying on interface-stabilized oxygen vacancies, we have created a new type of 2DEG at the heterointerface between SrTiO3 and a spinel γ-Al2O3 epitaxial film with compatible oxygen ion sublattices. This 2DEG exhibits an electron mobility exceeding 100000 cm2·V-1·s-1, more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces. Our findings pave the way for the design of high-mobility all-oxide electronic devices and open a route toward the studies of mesoscopic physics with complex oxides.
    Review of magnetic properties and magnetocaloric effect in the intermetallic compounds of rare earth with low boiling point metals
    Ling-Wei Li(李领伟)
    Chin. Phys. B, 2016, 25 (3): 037502.   DOI: 10.1088/1674-1056/25/3/037502
    Abstract1125)   HTML    PDF (1443KB)(1083)      

    The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively investigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s) (Zn, Mg, and Cd). Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi2B2C superconductors is also presented.

    Cited: Web of science (157)
    Development and application of ferrite materials for low temperature co-fired ceramic technology
    Zhang Huai-Wu (张怀武), Li Jie (李颉), Su Hua (苏桦), Zhou Ting-Chuan (周廷川), Long Yang (龙洋), Zheng Zong-Liang (郑宗良)
    Chin. Phys. B, 2013, 22 (11): 117504.   DOI: 10.1088/1674-1056/22/11/117504
    Abstract762)      PDF (4913KB)(3918)      
    Development and application of ferrite materials for low temperature co-fired ceramic (LTCC) technology are discussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 ℃. These ferrite materials are research focuses and are applied in many ways in electronics.