Entropy per particle spikes in the transition metal dichalcogenides
Department of Physics, Taras Shevchenko National University of Kyiv 6 Academician Glushkov Ave., Kyiv 03680, Ukraine
V.P. Gusynin and S.G. Sharapov
Bogolyubov Institute for Theoretical Physics of the National Academy of Science of Ukraine 14-b Metrolohichna Str., Kyiv 03680, Ukraine
CNR-SPIN, University “Tor Vergata”, Viale del Politecnico 1, I-00133 Rome, Italy
Received December 27, 2017
We derive a general expression for the entropy per particle as a function of chemical potential, temperature and gap magnitude for the single layer transition metal dichalcogenides. The electronic excitations in these mate-rials can be approximately regarded as two species of the massive or gapped fermions. Inside the smaller gap there is a region with zero density of states where the dependence of the entropy per particle on the chemical potential exhibits a huge dip-and-peak structure. The edge of the larger gap is accompanied by the discontinuity of the density of states that results in the peak in the dependence of the entropy per particle on the chemical potential. The specificity of the transition metal dichalcogenides makes possible the observation of these features at rather high temperatures order of 100 K. The influence of the uniaxial strain on the entropy per particle is discussed.
PACS: 73.43.Cd Theory and modeling; PACS: 68.60.Dv Thermal stability; thermal effects; PACS: 65.40.gd Entropy.