中国物理B ›› 2005, Vol. 14 ›› Issue (11): 2329-2334.doi: 10.1088/1009-1963/14/11/031
钱小陵1, 胡凤霞2, 高炬3, 王光军4, 孙继荣4, 沈保根4, 成昭华4
Hu Feng-Xia (胡凤霞)abc, Qian Xiao-Ling (钱小陵)a, Wang Guang-Jun (王光军)b, Sun Ji-Rong (孙继荣)b, Shen Bao-Gen (沈保根)b, Cheng Zhao-Hua (成昭华)b, Gao Ju (高炬)c
摘要: Magnetoresistances and magnetic entropy changes in NaZn13-type compounds La(Fe1-xCox)11.9Si1.1(x=0.04, 0.06, and 0.08) with Curie temperatures of 243\,K, 274\,K, and 301\,K, respectively, are studied. The ferromagnetic ordering is accompanied by a negative lattice expansion. Large magnetic entropy changes in a wide temperature range from \sim 230\,K to \sim 320\,K are achieved. Raising Co content increases the Curie temperature but weakens the gnetovolume effect, thereby causing a decrease in magnetic entropy change. These materials exhibit a metallic character below TC, whereas the electrical resistance decreases abruptly and then recovers the metal-like behaviour above TC. Application of a magnetic field retains the transitions via increasing the ferromagnetic ordering temperature. An isothermal increase in magnetic field leads to an increase in electrical resistance at temperatures near but above TC,which is a consequence of the field-induced metamagnetic transition from a paramagnetic state to a ferromagnetic state.
中图分类号: (Metals and alloys)