2022/06/25 by Bera, Satyabrata, Pradhan, Suman Kalyan, Khan, Md Salman +7
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2206.12552
We have investigated the nature of ferromagnetic order and phase transitions in two dimensional (2D) van der Waals (vdW) layered material, Fe4GeTe2 through measurements of magnetization, magneto-caloric Effect (MCE), and heat capacity. Fe4GeTe2 hosts a complex magnetic phase with two distinct transitions: paramagnetic to ferromagnetic at around TC ∼ 266 K and another spin reorientation transition (SRT) at around TSRT ∼ 100 K. The magnetization measurements shows a prominent thermal hysteresis in proximity to TSRT at H∥ c, which implies the first-order nature of SRT. Reasonable MCE has been observed around both transition temperatures ( at around TC, -ΔSMmax = 1.95 and 1.99 J.Kg-1K-1 and at around TSRT, -ΔSMmax= 3.9 and 2.4 J.Kg-1K-1 along H∥ ab and H∥ c respectively) at 50 kOe magnetic field change. The above results reveal higher MCE value at TSRT compared to the values of MCE at TC. The scaling analysis of MCE at TC, shows that the rescaled ΔSM (T, H) follow a universal curve confirming the second-order character of the ferromagnetic transition. The same scaling analysis of MCE breaks down at TSRT suggesting that SRT is not a second order phase transition. The exponent n from field dependence of magnetic entropy change presents a maximum of |n|>2 confirming the first-order nature of SRT.