Tin telluride: A weakly co-elastic metal

E. K.H. Salje, D. J. Safarik, K. A. Modic, J. E. Gubernatis, J. C. Cooley, R. D. Taylor, B. Mihaila, A. Saxena, T. Lookman, J. L. Smith, R. A. Fisher, M. Pasternak, C. P. Opeil, T. Siegrist, P. B. Littlewood, J. C. Lashley

Research output: Contribution to journalArticlepeer-review

Abstract

We report resonant ultrasound spectroscopy (RUS), dilatometry/ magnetostriction, magnetotransport, magnetization, specific-heat, and S 119 n Mössbauer spectroscopy measurements on SnTe and Sn0.995 Cr 0.005 Te. Hall measurements at T=77K indicate that our Bridgman-grown single crystals have a p -type carrier concentration of 3.4× 1019 cm -3 and that our Cr-doped crystals have an n -type concentration of 5.8× 1022 cm-3. Although our SnTe crystals are diamagnetic over the temperature range 2≤T≤1100K, the Cr-doped crystals are room-temperature ferromagnets with a Curie temperature of 294 K. For each sample type, three-terminal capacitive dilatometry measurements detect a subtle 0.5μm distortion at Tc ≈ 85K. Whereas our RUS measurements on SnTe show elastic hardening near the structural transition, pointing to co-elastic behavior, similar measurements on Sn0.995 Cr 0.005 Te show a pronounced softening, pointing to ferroelastic behavior. Effective Debye temperature, θD, values of SnTe obtained from S 119 n Mössbauer studies show a hardening of phonons in the range 60-115 K (θD =162K) as compared with the 100-300 K range (θD =150K). In addition, a precursor softening extending over approximately 100 K anticipates this collapse at the critical temperature and quantitative analysis over three decades of its reduced modulus finds Δ C44 / C44 =A |( T-T0 )/T0 | with κ=0.50±0.02, a value indicating a three-dimensional softening of phonon branches at a temperature T0 ∼75K, considerably below Tc. We suggest that the differences in these two types of elastic behaviors lie in the absence of elastic domain-wall motion in the one case and their nucleation in the other.

Original languageEnglish
Article number184112
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume82
Issue number18
DOIs
StatePublished - 18 Nov 2010

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