Complex transport properties of the Ni1.92Mn1.56Sn0.52 Heusler alloy and its magnetic behavior

The electric and thermal transport properties (electric resistivity ρ, magneto-resistance MR, Hall coefficient RH and anomalous Hall effect, thermal conductivity Κ and Seebeck coefficient S) of the off-stoichiometric Ni1.92Mn1.56Sn0.52 Heusler alloy were measured in a wide temperature and magnetic field range. The simultaneous measurement of several transport and magnetic properties offers a possibility to combine information arising from the received experimental results. The phonon and the charge carriers parts of complex temperature dependence of thermal conductivity K(T) were consistently separated using the Lorentz factor and temperature dependence of resistivity ρ(T). The positive values of the Hall coefficient RH has been determined in martensite phase of the alloy at low temperatures. RH reaches zero value at temperature range where the so-called “paramagnetic gap” was observed and the negative value of RH was detected in austenite phase. Temperature dependence of the Hall coefficient RH(T) was used to derive both, the density and the mobility of charge carriers. The standard relations were used to describe the measured temperature dependence of the Seebeck coefficient. All the received result point to an important role of changes in electronic structure of the alloy in all the studied transport effects. A scenario of the complex behavior of the transport properties of the Heusler alloy based on a possible existence of an energy gap in electronic structure is discussed.