中国物理B ›› 2020, Vol. 29 ›› Issue (4): 47503-047503.doi: 10.1088/1674-1056/ab7da1

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Magnetocaloric effect and critical behavior of the Mn-rich itinerant material Mn3GaC with enhanced ferromagnetic interaction

Pengfei Liu(刘鹏飞), Jie Peng(彭杰), Mianqi Xue(薛面起), Bosen Wang(王铂森)   

  1. 1 Hunan Key Laboratory for Micro-Nano Energy Materials and Devices and School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, China;
    2 Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
    3 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2020-01-19 修回日期:2020-03-02 出版日期:2020-04-05 发布日期:2020-04-05
  • 通讯作者: Bosen Wang E-mail:bswang@iphy.ac.cn

Magnetocaloric effect and critical behavior of the Mn-rich itinerant material Mn3GaC with enhanced ferromagnetic interaction

Pengfei Liu(刘鹏飞)1,2, Jie Peng(彭杰)1, Mianqi Xue(薛面起)2, Bosen Wang(王铂森)3   

  1. 1 Hunan Key Laboratory for Micro-Nano Energy Materials and Devices and School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, China;
    2 Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
    3 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2020-01-19 Revised:2020-03-02 Online:2020-04-05 Published:2020-04-05
  • Contact: Bosen Wang E-mail:bswang@iphy.ac.cn

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摘要： We revisit the reversible magnetocaloric effect of itinerant ferromagnet Mn3GaC near the ferromagnetic to paramagnetic phase transition by adopting the experimental and theoretical methods and critical behavior of Mn-rich Mn3GaC with an enhanced FM interaction. Landau theory model cannot account for temperature dependent magnetic entropy change which is estimated from thermal magnetic methods only considering magnetoelastic coupling and the electron-electron interaction, apart from molecular mean-field model. Critical behavior is studied by adopting the modified Arrott plot, Kouvel-Fisher plot, and critical isotherm analysis. With these critical exponents, experimental data below and above Tc collapse into two universal branches, fulfilling the single scaling equation m=f±(h), where m and h are renormalized magnetization and field. Critical exponents are confirmed by Widom scaling law and just between mean-field model and three-dimensional Heisenberg model, as the evidence for the existence of long-range ferromagnetic interaction. With increasing the Mn content, Tc increases monotonously and critical exponents increases accordingly. The exchange distance changes from J(r) ～ r-4.68 for x = 0 to J(r) ～ r-4.71 for x = 0.08, respectively, which suggests the competition of the Mn-Mn direct interaction and the itinerant Mn-C-Mn hybridization. The possible mechanism is proposed.

关键词: magnetocaloric effect, critical behavior, Mn3GaC

Abstract: We revisit the reversible magnetocaloric effect of itinerant ferromagnet Mn3GaC near the ferromagnetic to paramagnetic phase transition by adopting the experimental and theoretical methods and critical behavior of Mn-rich Mn3GaC with an enhanced FM interaction. Landau theory model cannot account for temperature dependent magnetic entropy change which is estimated from thermal magnetic methods only considering magnetoelastic coupling and the electron-electron interaction, apart from molecular mean-field model. Critical behavior is studied by adopting the modified Arrott plot, Kouvel-Fisher plot, and critical isotherm analysis. With these critical exponents, experimental data below and above Tc collapse into two universal branches, fulfilling the single scaling equation m=f±(h), where m and h are renormalized magnetization and field. Critical exponents are confirmed by Widom scaling law and just between mean-field model and three-dimensional Heisenberg model, as the evidence for the existence of long-range ferromagnetic interaction. With increasing the Mn content, Tc increases monotonously and critical exponents increases accordingly. The exchange distance changes from J(r) ～ r-4.68 for x = 0 to J(r) ～ r-4.71 for x = 0.08, respectively, which suggests the competition of the Mn-Mn direct interaction and the itinerant Mn-C-Mn hybridization. The possible mechanism is proposed.

Key words: magnetocaloric effect, critical behavior, Mn3GaC

中图分类号:  (Metals and alloys)

  • 75.20.En
75.30.Sg (Magnetocaloric effect, magnetic cooling) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects)