Field-induced tricritical phenomenon of the van der Waals magnetic material CrVI6

The two dimensional (2D) van der Waals material (vdW) CrVI6 nanoflake exhibits a Bloch-type skyrmion, demonstrating significant potential for advanced spintronics and high-density magnetic memory applications. However, the intricate magnetic interactions remain controversial. In order to understand the magnetic interactions, we conduct a systematic study of the critical phenomena in CrVI6 single crystal near the Curie temperature (TC). A set of reliable critical exponents (beta = 0.287(7), gamma = 0.944(7), and delta = 4.36(3) at TC = 50.71 (3)) was obtained using the Kouvel-Fisher technique, the reliability and consistency of which are examined using the modified Arrott plot method, the Widom scaling law and the scaling equations. The obtained critical exponents align with the tricritical mean-field theory, indicating a field-induced tricritical phenomenon at the boundary between the first-order and second-order phase transitions. Furthermore, the tricritical point (TCP) of HTCP = 2000 Oe is obtained at TC. The analysis of the critical behavior suggests a long-range magnetic coupling in CrVI6, with the magnetic exchange distance J(r) decaying as J(r) approximate to r-4.45. These findings provide insight for clarifying the complex magnetic couplings in CrVI6.