[Lecture] Large magnetoresistance and magnetothermal conductivity in the Ni-Mn-In ferromagnetic shape memory alloys
Speaker: Xixiang Zhang
Date: November 11th (Thursday)
Time: 10:00 am
Location: 215, MSE Building
Abstract: There are large magneto-electrical resistance and large magnetothermal conductivity in NiMnIn Heusler alloy single crystals, a ferromagnetic shape memory alloy (FMSA). Upon cooling, these alloys show a martensitic transformation, which is accompanied by a ferromagnetic metal ferrimagnetic poor-metal transition. This transformation is reversible with a thermal hysteresis. Most strikingly, the martensitic transformation can be shifted to lower temperature and even totally suppressed, when cooled in an external magnetic field. The magnetic field-induced phase transformation leads to a large, negative magnetoresistance and a large magnetothermal conductivity up to 86% and 120% respectively in an abroad temperature range. The heat capacity measurements under different magnetic fields indicate that the large magnetotransport properties are due to the increase of the free electronic density, which strongly suggests an existence of superzone gap in the low temperature, ferrimagnetic martensite.
