Electronic properties ofTiSi2single crystals at low temperatures

Publisher Website
Google Scholar
Abstract
We report measurements of Hall effect, transverse magnetoresistance, and specific heat on high-quality TiSi2 (C54 phase) single crystals at low temperatures. We used crystals with low residual resistivity (typically ρ4.2K=0.15 μΩ cm) and magnetic fields (B) up to 20 T. These facts allowed us to study the electronic properties from the low (ωcτ≪1) to the high field regime (ωcτ≳1, ωc=eB/m* being the cyclotron frequency and τ the electron relaxation time) as a function of magnetic-field strength and temperature. The low field Hall coefficient RH is negative, almost constant RH=-(0.5±0.1)×10−10 m3/C between 100 and 300 K and it changes sign at ∼30 K. The angular dependence of magnetoresistance shows either minima or maxima when the magnetic field is parallel to the principal crystallographic axes. These structures are, however, less pronounced than in other silicides, such as PdSi2 and NbSi2, and this suggests only a weak anisotropy of the TiSi2 Fermi surface. The galvanomagnetic properties behave consistently with band-structure calculations of Mattheiss and Hensel [Phys. Rev. B 39, 7754 (1989)] who found that TiSi2 is a compensated metal with only closed orbits for the Fermi electrons. Using a simple two-band model we estimated, from the low field magnetoresistance, carrier density ne=nh=(0.45–0.52)×1022 cm−3 assuming equal concentration of electrons and holes. Low temperatures (1.6<T<22 K) specific-heat (Cp) measurements fit a linear Cp/T=γ+βT2 dependence, with γ=3.35±0.05 mJ/K2 mol and β=0.0201±0.0005 mJ/K4 mol. From these parameters we estimated the Debye temperature ΘD=662±4 K and the renormalized electronic density of states at the Fermi surface N(