Galvanomagnetic effects in single-crystal ZrB 2

Abstract

The magnetoresistance and Hall effect of ZrB 2 crystals with resistivity ratios ( ρ 300 ρ 4.2 ) of ~100 are studied over the temperature range 1.3–300°K, at magnetic fields to 12.7 kG. Room-temperature resistivities of the samples are 2.9–3.4 μΩ−cm. At 4.2°K the maximum observed magnetoresistance ( Δρ ρ o ) is ~45. The Hall coefficients approach constant values in the high-field region and the magnetic field dependence of the magnetoresistance is approximately quadratic. No sharp minima in the orientation dependence of the transverse magnetoresistance are observed: thus ZrB 2 behaves like a compensated semimetal with no open orbits in its Fermi surface. Using Hall and magnetoresistive coefficients the effective electron concentration is found to be 0.06 per unit cell. The mobilities of the electrons and holes are of the same order of magnitude.