Semiconductor-metal transition and the onset of itinerant ferromagnetism in the Heusler phases TiCoSn-TiCoSb

Abstract

The magnetic and transport properties of the TiCoSnxSb1-x solid solutions with the cubic MgAgAs structure have been studied, and show the onset of ferromagnetism associated with a semiconductor to metal transition, keeping the same 3d elements and varying the number of s-p electrons. The transition from TiCoSn ferromagnetic metal to the non-magnetic semiconductor TiCoSb occurs through an intermediate metallic Pauli-like state. The variations of the Curie temperature as a function of saturation and effective paramagnetic moments are related to the itinerant ferromagnetism model. A comparison is made with the TiCoxNi1-xSn series, where the transition occurs directly from ferromagnetic metal to semiconducting state.

Thermoelectric Properties of (Ti,Zr,Hf)CoSb Type Half-Heusler Compounds

“…It seems that these impurity phases are due to the evaporation of antimony at arc melting. Each lattice parameter of TiCoSb, ZrCoSb, and HfCoSb is 0.58845, 0.60648, and 0.60411 nm, respectively, which almost agree with the literature data of TiCoSb, 1,2,8,[18][19][20][21] and ZrCoSb and HfCoSb. 3,30) We detected the impurity phases on TiCoSb 28) and HfCoSb but not for ZrCoSb from the surface observation by SEM.…”

“…3. In comparison to the value of the hightemperature resistivity reported in the literatures, 8,19,20,24,28,31) our measured values are rather small. The lowest resistivity is measured on HfCoSb.…”

“…According to Terada et al, 17,18) TiCoSb shows paramagnetism nearly independent of temperature and does not have a magnetic moment above 80 K. Also, they have reported that the magnitude of the magnetic susceptibility increases by a heat treatment, which is due to a small amount of a precipitated ferromagnetic phase. Similar magnetic property of TiCoSb has been demonstrated in the past reports on TiCoSn x Sb 1Àx , 8,19) TiCo 1Àx Ni x Sb 20,21) solid solution, and so on. 22) The thermoelectric properties of TiCoSb have been reported in large number below the room temperature, 19,20,23) and there are data by Xia et al 24) and Zhou et al 21) for temperature up to 800 and 900 K. Until now, we have studied these 18 valence electron systems.…”

“…Similar magnetic property of TiCoSb has been demonstrated in the past reports on TiCoSn x Sb 1Àx , 8,19) TiCo 1Àx Ni x Sb 20,21) solid solution, and so on. 22) The thermoelectric properties of TiCoSb have been reported in large number below the room temperature, 19,20,23) and there are data by Xia et al 24) and Zhou et al 21) for temperature up to 800 and 900 K. Until now, we have studied these 18 valence electron systems. [25][26][27][28] In this paper, we discuss the thermoelectric properties of (Ti, Zr, Hf)CoSb systems at high temperature region up to 973 K.…”

Mössbauer spectroscopic study of half-Heusler compounds

“…The half-Heusler compounds CoMnSb, NiMnSb and CoTiSb have been synthesized by arcmelting of proper amounts of the constituents under purified argon atmosphere [4,5]. The same preparation procedure has been used to produce the polycrystalline samples of GdAuSn, MnAuSn and the granular material consisting of their mixture.…”