Experimental study of criticality in the metamagnet CsCoCl3·2D2O

This paper reports the results of a neutron-diffraction study on the critical behavior of the induced magnetization $M$ and the staggered magnetization $M_{\mathrm{st}}$ along the metamagnetic phase transition in CsCo${\mathrm{Cl}}_3$·2${\mathrm{D}}_2$O. This phase transition contains a tricritical point (TCP) at $T_t=1.85\mathrm{}$ K and $H_t=2.70\mathrm{}$ kOe. Critical exponents and amplitudes are obtained in the critical region ($\alpha ,\beta$) and at the TCP (${\alpha }_t,{\beta }_t,{\beta }_1,{\beta }_u,\phi$). It is shown that the critical behavior along the critical line is in agreement with three-dimensional Ising behavior up to the TCP. In the vicinity of the TCP, crossover is observed. The tricritical behavior cannot be characterized by classical exponents. The validity of the exponents is tested by an analysis of the various tricritical scaling functions.