Investigations of the coupling of spin-orbital in MgTi2O4 by the magnetic entropy measurements

Abstract

Single phase MgTi 2 O 4 compound was synthesized by spark plasma sintering (SPS) method. The temperature dependence of the magnetic susceptibility and specific heat measurements show that MgTi 2 O 4 takes place in phase transition at 258 K. Magnetic entropy measurements show that the change of magnetic entropy ΔSM is positive and ΔSM increases more quickly than H2/3 near the transition; while ΔSM is negative and |ΔSM| (the absolute value) increases slowly with applied field increasing at lower temperature. The change of ΔSM at different temperature range is suggested to be related not only to spin entropy change, but also orbital entropy change. The magnetic phases of MgTi 2 O 4 are suggested to be Pauli paramagnetic, collinear antiferromagnetic and non-collinear antiferromagnetic order with temperature decrease.