Tricritical-point phase diagram in PrCu9Sn4

Tricritical phenomenon appearing in multiple phases is a fundamental and attractive issue in condensed-matter physics. In this work, a field-modulated tricritical phenomenon is realized in single-crystal PrCu9Sn4. The magnetization under variable directions of field indicates strong magnetic anisotropy in PrCu9Sn4, which reveals ferromagnetic coupling for H//c. A paramagnetic-to-ferromagnetic magnetic transition occurs with H//c at T (C) = 11.7 K, which is evidenced to be of a first-ordered type. The systematical study of the critical behavior gives that beta = 0.195(8), gamma = 0.911(1), and delta = 0.0592(1) for H//c consistent with a tricritical mean-field model, which suggests a field-modulated tricritical phenomenon. A detailed H - T phase diagram around the tricritical point (TCP) is constructed for single-crystal PrCu9Sn4 for H//c, where ferromagnetic state, forced ferromagnetic phase and paramagnetic state meet at the TCP (H (tr) = 799 kOe, T (tr) = 11.3 K). The single-crystal PrCu9Sn4 supplies a platform to deep investigate the field-modulated magnetic couplings and tricritical phenomenon.