Critical phenomenon of the ferromagnet Cr2Te3 with strong perpendicular magnetic anisotropy

Abstract

Chromium telluride ${\mathrm{Cr}}_x{\mathrm{Te}}_y$ has great potential applications in spintronics due to its intrinsic ferromagnetism and strong magnetic anisotropy. In this study, we systematically investigate magnetic properties of a ferromagnetic ${\mathrm{Cr}}_2{\mathrm{Te}}_3$ single crystal with strong perpendicular magnetic anisotropy (PMA). Apart from ferromagnetic-to-paramagnetic (FM-PM) transitions at $T_C\sim 181$ K for both $H//c$ and $H//ab$, other exotic magnetic behaviors are revealed, such as a field-modulated first-order transition uncovered by the anisotropic magnetization, a canted FM coupling rather than previously reported spin-glass behavior demonstrated by the ac susceptibility. Furthermore, anisotropic magnetization reveals significant PMA stronger than any other $\mathrm{Cr}$-based transition metal chalcogenide, with a negligible saturation field for $H//c$ but a distinct one up to 155 kOe for $H//ab$. Critical exponents $\beta =0.340(5)$, $\gamma =1.114(1)$, and $\delta =4.504(5)$ are obtained for $H//c$, which fall between the three-dimensional (3D)-$XY$ and 3D-Ising models indicative of anisotropic magnetic coupling. An $H$-$T$ phase diagram of the ${\mathrm{Cr}}_2{\mathrm{Te}}_3$ single crystal is constructed for $H//c$, which distinguishes canted FM1, canted FM2, forced FM (FFM), and PM phases. The phase diagram indicates that the transition to the canted FM2 under lower fields is of a first-order type, which is suppressed into a second-order one by the external magnetic field. The multiple phase transitions and complex magnetic structures is suggested to derive from the competition between the intralayered superexchange (FM couplings) and the interlayered direct interaction (AFM coupling). The various magnetic configurations and strong PMA make ${\mathrm{Cr}}_2{\mathrm{Te}}_3$ highly promising for spintronic device applications.