Existence of electron and hole pockets and partial gap opening in the correlated semimetal Ca3Ru2O7

Abstract

The electronic band structure of correlated Ca3Ru2O7 featuring an antiferromagnetic as well as a structural transition has been determined theoretically at high temperatures, which has led to the understanding of the remarkable properties of Ca3Ru2O7 such as the bulk spin valve effects. However, its band structure and Fermi surface (FS) below the structural transition have not been resolved even though a FS consisting of electron pockets was found experimentally. Here we report magneto electrical transport and thermoelectric measurements with the electric current and temper- ature gradient directed along a and b axes of an untwined single crystal of Ca3Ru2O7 respectively. The thermopower obtained along the two crystal axes were found to show opposite signs at low temperatures, demonstrating the presence of both electron and hole pockets on the FS. In addition, how the FS evolves across T* = 30 K at which a distinct transition from coherent to incoherent behavior occurs was also inferred - the Hall and Nernst coefficient results suggest a temperature and momentum dependent partial gap opening in Ca3Ru2O7 below the structural transition, with a pos- sible Lifshitz transition occurring at T*. The experimental demonstration of a correlated semimetal ground state in Ca3Ru2O7 calls for further theoretical studies of this remarkable material.

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• Anomalous electron transport in epitaxial NdNiO${}_3$ films
• Cooperative Interactions Govern the Fermiology of the Polar Metal Ca${}_3$Ru${}_2$O${}_7$
• Electronic reconstruction forming a $C_2$-symmetric Dirac semimetal in Ca${}_3$Ru${}_2$O${}_7$
• Ultrafast quasiparticle dynamics in correlated semimetal Ca${}_3$Ru${}_2$O${}_7$
• Resonant Inelastic X-ray Scattering Study of Ca${}_3$Ru${}_2$O${}_7$
• Strain control of a bandwidth-driven spin reorientation in Ca${}_3$Ru${}_2$O${}_7$
• Two-carrier Magnetoresistance: Applications to Ca${}_3$Ru${}_2$O${}_7$
• Nonlinear Transport Signatures of Hidden Symmetry Breaking in a Weyl Altermagnet
• Probing Hidden Symmetry and Altermagnetism with Sub-Picometer Sensitivity via Nonlinear Transport
• A simplified method characterizing magnetic ordering modulated photo-thermoelectric response in noncentrosymmetric semimetal Ca3Ru2O7