Magnetotransport in single-crystal half-Heusler compounds

Abstract

We present the results of electrical resistivity and Hall effect measurements on single crystals of HfNiSn, TiPtSn, and TiNiSn. Semiconducting behavior is observed in each case, involving the transport of a small number of highly compensated carriers. Magnetization measurements suggest that impurities and site disorder create both localized magnetic moments and extended paramagnetic states, with the susceptibility of the latter increasing strongly with reduced temperature.The magnetoresistance is sublinear or linear in fields ranging from 0.01 -9 Tesla at the lowest temperatures. As the temperature increases, the normal quadratic magnetoresistance is regained, initially at low fields, and at the highest temperatures extending over the complete range of fields.The origin of the vanishingly small field scale implied by these measurements remains unknown, presenting a challenge to existing classical and quantum mechanical theories of magnetoresistance.

Thermoelectric and Thermophysical Properties of TiCoSb-ZrCoSb-HfCoSb Pseudo Ternary System Prepared by Spark Plasma Sintering

“…The of TiCoSb, ZrCoSb and HfCoSb are larger than those of as-cast samples reported in the previous study. 11) It is well known that the annealing condition 10,[13][14][15] and the deviation from the stoichiometric composition 6) have much effect on the thermoelectric properties of the half-Heusler compounds. For example, the of TiCoSb tends to increase with decreasing the Co/Sb ratio and with increasing the Ti/Sb ratio.…”

“…So, TiCoSb is expected to have a larger thermoelectric power S. From the literatures, [6][7][8][9][10][11] TiCoSb has a negative thermoelectric power. The improvement of the structural disorder 12) by annealing has been reported on MNiSn system [13][14][15] and TiCoSb system. 10) The thermoelectric properties of ZrCoSb and HfCoSb have been reported only for the electrical resistivity and thermoelectric power below room temperature.…”

Electronic Structure and X-Ray Photoemission Spectra of MPtSn (M = Ti, Zr, Hf)

“…Only recently the transport behavior for TiNiSn, HfNiSn and TiPtSn were reported by Ahilan et al [5], which were measured on single-crystalline samples. All of them show the temperature dependences of the electrical resistivity having the behavior typical of n-type semiconductors.…”

“…So far the transport properties, except TiPtSn [5], have practically been not known for the Pt-based ternaries. Only a preliminary report on the temperature dependence of the resistivity in this group of compounds was presented in the literature, but without any deeper analysis of the observed dependences [2].…”

“…Compounds considered in this work have z = 18, i.e. the most favorable number of valence electrons to form the narrow-gap semiconductors [5]. * corresponding author; e-mail: szajek@ifmpan.poznan.pl…”