Magnetic and thermal properties of alloys close in composition to the spin gapless semiconductor Mn2CoAl
A. A. Semiannikova1, N. I. Kourov1, A. V. Korolev1, Yu. A. Perevozchikova1, E. B. Marchenkova1, P. S. Korenistov1, A. N. Domozhirova1, and V. V. Marchenkov1,2
1M. N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences Ekaterinburg 620108, Russia
2Ural Federal University, Ekaterinburg 620108, Russia
Received September 15, 2020, published online November 24, 2020
The field dependence of magnetization at T = 4.2 K and in magnetic fields of up to 70 kOe, temperature dependences of magnetization (2 K < T < 300 K), heat capacity (2 K < T < 30 K) and magnetic susceptibility (2 K < T < 1000 K) for Mn1.99Co0.96Al1.05 and Mn1.79Co1.25Al0.96 alloys, closed in composition to the Mn2CoAl spin gapless semiconductor, were studied. Alloys studied were demonstrated to be the band ferromagnets. Their high-field (H > 11 kOe) magnetization is described in the Stoner models with the Rhodes–Wohlfarth parameter pRW = 1.3 for Mn1.99Co0.96Al1.05 and pRW = 2.3 for Mn1.79Co1.25Al0.96. When the composition deviates from the stoichiometric Mn2CoAl, the spontaneous moment decreases slightly, the effective moment, on the contrary, increases. In this case, a negative sign of the temperature-independent component of the paramagnetic susceptibility is observed. The density of states n(EF) at Fermi level and the Debye temperature ΘD of studied alloys have the usual values for 3d-metal alloys.
Key words: spin gapless semiconductor, Mn2CoAl, magnetization, magnetic susceptibility, heat capacity.