Multiple first-order metamagnetic transitions and quantum oscillations in ultrapure

TL;DR

This study investigates quantum oscillations and metamagnetic transitions in ultra-clean Sr3Ru2O7, revealing small Fermi surface changes, unusual resistivity behavior near the critical point, and the influence of disorder on phase transitions.

Contribution

It provides detailed measurements of quantum oscillations and resistivity near the metamagnetic transition in Sr3Ru2O7, highlighting the role of disorder and identifying first-order phase boundaries.

Findings

Quantum oscillations show frequency shifts across the transition.

Resistivity exhibits a minimum below 1 K near the critical field.

Disorder level affects the sharpness of the anomalous behavior.

Abstract

We present measurements on ultra clean single crystals of the bilayered ruthenate metal Sr3Ru2O7, which has a magnetic-field-tuned quantum critical point. Quantum oscillations of differing frequencies can be seen in the resistivity both below and above its metamagnetic transition. This frequency shift corresponds to a small change in the Fermi surface volume that is qualitatively consistent with the small moment change in the magnetisation across the metamagnetic transition. Very near the metamagnetic field, unusual behaviour is seen. There is a strong enhancement of the resistivity in a narrow field window, with a minimum in the resistivity as a function of temperature below 1 K that becomes more pronounced as the disorder level decreases. The region of anomalous behaviour is bounded at low temperatures by two first-order phase transitions. The implications of the results are discussed. PACS: 68.35.Rh, 71.27.+a, 72.15.-v, 74.70.Pq