Perturbation-tuned triple spiral metamagnetism and tricritical point in kagome metal ErMn6Sn6

Kagome materials are of topical interest for their diverse quantum properties linked with correlated magnetism and topology. Here, we report anomalous hydrostatic pressure (p) effect on ErMn6Sn6 through isobaric and isothermal-isobaric magnetization measurements. Magnetic field (H) suppresses antiferromagnetic TN while simultaneously enhancing the ferrimagnetic TC by exhibiting dual metamagnetic transitions, arising from the triple-spiral-nature of Er and Mn spins. Counter-intuitively, pressure enhances both TC and TN with a growth rate of 74.4 K GPa−1 and 14.4 K GPa−1 respectively. Pressure unifies the dual metamagnetic transitions as illustrated through p-H phase diagrams at 140 and 200 K. Temperature-field-pressure (T-H, T-p) phase diagrams illustrate distinct field- and pressure-induced critical points at (Tcr = 246 K, Hcr = 23.3 kOe) and (Tcr = 435.8 K, pcr = 4.74 GPa) respectively. An unusual increase of magnetic entropy by pressure around Tcr and a putative pressure-induced tricritical point pave a unique way of tuning the magnetic properties of kagome magnets through simultaneous application of H and p. The kagome metal ErMn6Sn6 is known to display interesting physics. Here, the simultaneous effect of a magnetic field and pressure is investigated, revealing the role of the spiral behavior of magnetic layers on magnetic transition temperatures