Nonlinear Pauli susceptibilities in Sr3Ru2O7 and universal features of itinerant metamagnetism

Abstract

We report, for the first time, measurements of the third order, χ3 and fifth order, χ5, susceptibilities in an itinerant oxide metamagnet, Sr3Ru2O7 for magnetic fields both parallel and perpendicular to the c-axis. These susceptibilities exhibit maxima in their temperature dependence such that T1 ≈ 2T3 ≈ 4T5 where the Ti are the position in temperature where a peak in the i-th order susceptibility occurs. These features taken together with the scaling of the critical field with the temperature T1 observed in a diverse variety of itinerant metamagnets find a natural explanation in a single band model with one Van Hove singularity (VHS) and onsite repulsion U . The separation of the VHS from the Fermi energy ∆, sets a single energy scale, which is the primary driver for the observed features of itinerant metamagnetism at low temperatures.PACS numbers: 75.30. Mb, 75.20.Hr Metamagnetism (MM), the sudden rise of the magnetization at a critical field, is a phenomenon observed in a diverse range of metals, and extensively studied in both d and f-electron based itinerant systems. 1 In many itinerant metamagnets as is the case with heavy fermion materials there is a clear presence of local moments, often antiferromagnetically coupled (as ascertained, for instance, from a high temperature Curie Weiss plot), which however develop a strong net moment at the critical field, B c . The predominant antiferromagnetic correlations are strongly suppressed in high fields 2 with possibly new ferromagnetic correlations arising 3 in the vicinity of B c . In contrast, itinerant electron MM can also be found in systems where there is no clear evidence for local moments 4 as in the case of the metallic oxide Sr 3 Ru 2 O 7 (SRO). Given this fundamental distinction between the two cases it would be natural to ask what if any universal features and/or significant differences exist in the nature of their metamagnetism.The bilayer ruthenate SRO shows a complex phase diagram where multiple MM transitions may be tuned by varying the angle of the applied field with respect to the crystal axes. Upon increasing temperature, these firstorder MM transitions end at critical end points, which are themselves connected by a line of second order phase transitions. 5,6 Enclosed between these transition lines is an anomalous phase with unusual transport properties. The resistivity in this regime is anomalously high and shows anisotropy. Earlier attempts to understand these anomalous behaviors have been focused on the emergence of a nematic phase associated with the MM tran-sitions. 8-10 It has also been proposed that the anomalous phase can be viewed as a magnetic analogue of the spatially inhomogeneous superconducting Fulde Ferrell Larkin Ovchinnikov state. 11,12 Interestingly, recent magnetic neutron scattering showed that a spin-density-wave phase is induced in this regime of the phase diagram, 5 which provides a natural explanation for the strong resistivity anisotropy or the electronic nematic behavior.Although the nature of the anomalous phase rema...

Symmetry Analysis of Tensors in the Honeycomb Lattice of Edge-Sharing Octahedra

“…Even though we are taking a magnetic field derivative, this is still a zero-field tensor because we are evaluating the derivative in the zero-field limit (i.e., the infinitesimally small field is only being used to probe the zero-field ground state). Also note that while χ thermomag ijk is linear in the vectors H and ∇T , rank-3 tensors can also be quadratic in a given vector, such as the nonlinear magnetic susceptibility tensor [74][75][76][77]…”