Strong magnetic anisotropy, spin-phonon coupling and competing Ferromagnetic - Antiferromagnetic interaction in single crystalline Cr₂Te₃.

Cr_1+ẟTe₂ (0≤δ≤1) is a self-intercalating chromium chalcogenide series where, by varying δ, the system can be tuned from van-der Waals 2D magnet to a 3D magnet as well as magnetic ordering temperature, magnetic anisotropy changes significantly in this series. Most of the ordered materials have ferromegntic ground state. Usually, increasing δ results in an increase in ordering temperature. Cr₂Te₃ ( δ = ⅓) has maximum out-of-plane magnetic anisotropy energy in this series (Phys. Rev. M 4, 114001 (2020)). This is an absolute requirement for most spintronic applications. We have synthesised single crystals of Cr₂Te₃ by external flux, which shows two clear antiferromagnetic and ferromagnetic transitions around 180 K and spin canting at a lower temperature due to the highest degree of structural order. Earlier reports indicated only antiferromagnetic correlation in this ferromagnet. Strong magnetic out-of-plane anisotropy with negligible coercivity is also observed. The magnetic ground state in this material is governed by exchange interaction within the fully occupied and intercalated Cr-layers and between the two layers. In addition to that, we have investigated spin-phonon coupling across all the magnetic transitions using temperature-dependent Rman spectroscopy.