Studies of the temperature-pressure (T-p) phase diagram of metallic quantum ferromagnets have revealed that ferromagnetic quantum criticality is avoided in two ways [1]: either the transition becomes of the first-order at a tricritical point before being suppressed such as in UGe2 [2,3], or a transition to modulated magnetic phases appear such as in LaCrGe3 [4]. We have shown that the addition of a magnetic field (H) can restore quantum criticality at the end of “wings” in the T-p-H phase diagram in both UGe2 and LaCrGe3 [5]. Our careful study of the “wings” near the tricritical point reveal new rules that apply to the T-p-H phase diagram [6]. We discuss our experimental T-p-H phase diagrams of UGe2, LaCrGe3, and CeTiGe3 and how these compounds illustrate different strength of quantum fluctuations based on recent theoretical results [7].

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[3] H. Kotegawa et al. J. Phys. Soc. Jpn., 80, 8, 083703 (2011).
[4] V. Taufour et al. Phys. Rev. Lett. 117, 037207 (2016).
[5] U. S. Kaluarachchi et al. Nature Communications 8, 546 (2017).
[6] V. Taufour et al. Phys. Rev. B 94 060410 (2016).
[7] Belitz et al. Phys. Rev. Lett. 119, 267202 (2017).