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The magnetocaloric effect and critical behaviour of the Mn0.94Ti0.06CoGe alloy

Journal Article


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Abstract


  • Structural, magnetic and magnetocaloric properties of the Mn0.94Ti0.06CoGe alloy have been investigated using x-ray diffraction, DC magnetization and neutron diffraction measurements. Two phase transitions have been detected, at T-str = 235 K and T-C = 270 K. A giant magnetocaloric effect has been obtained at around Tstr associated with a structural phase transition from the low temperature orthorhombic TiNiSi-type structure to the high temperature hexagonal Ni2In-type structure, which is confirmed by neutron study. In the vicinity of the structural transition, at T-str, the magnetic entropy change, -Delta S-M reached a maximum value of 14.8 J kg(-1) K-1 under a magnetic field of 5 T, which is much higher than that previously reported for the parent compound MnCoGe. To investigate the nature of the magnetic phase transition around T-C = 270 K from the ferromagnetic to the paramagnetic state, we performed a detailed critical exponent study. The critical components gamma, beta and delta determined using the Kouvel-Fisher method, the modified Arrott plot and the critical isotherm analysis agree well. The values deduced for the critical exponents are close to the theoretical prediction from the mean-field model, indicating that the magnetic interactions are long range. On the basis of these critical exponents, the magnetization, field and temperature data around T-C collapse onto two curves obeying the single scaling equation M(H, epsilon) = epsilon(beta)f +/- (H/epsilon(beta+gamma)).

Authors


  •   Shamba, Precious (external author)
  •   Wang, Jian Li.
  •   Debnath, J C. (external author)
  •   Kennedy, Shane J. (external author)
  •   Zeng, R (external author)
  •   Md Din, M F. (external author)
  •   Hong, Fang (external author)
  •   Cheng, Zhenxiang
  •   Studer, Andrew J. (external author)
  •   Dou, Shi Xue

Publication Date


  • 2013

Citation


  • Shamba, P., Wang, J. L., Debnath, J. C., Kennedy, S. J., Zeng, R., Md Din, M. F., Hong, F., Cheng, Z., Studer, A. J. & Dou, S. X. (2013). The magnetocaloric effect and critical behaviour of the Mn0.94Ti0.06CoGe alloy. Journal of Physics: Condensed Matter, 25 (5), 056001-1-056001-7.

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1227&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/222

Start Page


  • 056001-1

End Page


  • 056001-7

Volume


  • 25

Issue


  • 5

Abstract


  • Structural, magnetic and magnetocaloric properties of the Mn0.94Ti0.06CoGe alloy have been investigated using x-ray diffraction, DC magnetization and neutron diffraction measurements. Two phase transitions have been detected, at T-str = 235 K and T-C = 270 K. A giant magnetocaloric effect has been obtained at around Tstr associated with a structural phase transition from the low temperature orthorhombic TiNiSi-type structure to the high temperature hexagonal Ni2In-type structure, which is confirmed by neutron study. In the vicinity of the structural transition, at T-str, the magnetic entropy change, -Delta S-M reached a maximum value of 14.8 J kg(-1) K-1 under a magnetic field of 5 T, which is much higher than that previously reported for the parent compound MnCoGe. To investigate the nature of the magnetic phase transition around T-C = 270 K from the ferromagnetic to the paramagnetic state, we performed a detailed critical exponent study. The critical components gamma, beta and delta determined using the Kouvel-Fisher method, the modified Arrott plot and the critical isotherm analysis agree well. The values deduced for the critical exponents are close to the theoretical prediction from the mean-field model, indicating that the magnetic interactions are long range. On the basis of these critical exponents, the magnetization, field and temperature data around T-C collapse onto two curves obeying the single scaling equation M(H, epsilon) = epsilon(beta)f +/- (H/epsilon(beta+gamma)).

Authors


  •   Shamba, Precious (external author)
  •   Wang, Jian Li.
  •   Debnath, J C. (external author)
  •   Kennedy, Shane J. (external author)
  •   Zeng, R (external author)
  •   Md Din, M F. (external author)
  •   Hong, Fang (external author)
  •   Cheng, Zhenxiang
  •   Studer, Andrew J. (external author)
  •   Dou, Shi Xue

Publication Date


  • 2013

Citation


  • Shamba, P., Wang, J. L., Debnath, J. C., Kennedy, S. J., Zeng, R., Md Din, M. F., Hong, F., Cheng, Z., Studer, A. J. & Dou, S. X. (2013). The magnetocaloric effect and critical behaviour of the Mn0.94Ti0.06CoGe alloy. Journal of Physics: Condensed Matter, 25 (5), 056001-1-056001-7.

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1227&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/222

Start Page


  • 056001-1

End Page


  • 056001-7

Volume


  • 25

Issue


  • 5