Magnetoentropic signatures of the textured metamagnetic phase of an antiferromagnetic polar metal : Ca3Ru2O7

This work is supported by a KAKENHI Grants-in-Aids for Scientific Research (Grant Nos. 17H06136, 18K04715, and 21H01033), and Core-to-Core Program (No. JPJSCCA20170002) from the Japan Society for the Promotion of Science (JSPS) and by a JST-Mirai Program (Grant No. JPMJMI18A3), and by the Max Planck Society. We report the magnetocaloric effect of a bilayered perovskite ruthenate Ca3Ru2O7 that has recently been recognized as an antiferromagnetic polar metal. The magnetic entropy change obtained from temperature dependence of the DC magnetization measurements shows peaks and valleys under the magnetic field near metamagnetic transitions, and enable us to map out a thermodynamic field–temperature phase-diagram. The area surrounded by the boundaries agrees well with a novel “metamagnetic texture” with spin modulation observed recently by small angle neutron scattering measurements. We demonstrate that a thermodynamically equilibrium state is realized between the antiferromagnetic and spin-polarized states throughout the metamagnetic transition in this polar metal. Postprint