Unusual Oscillation in Tunneling Magnetoresistance near a Quantum Critical Point in Sr$_3$Ru$_2$O$_7$

TL;DR

This study reports unusual oscillations in tunneling magnetoresistance near a quantum critical point in Sr$_3$Ru$_2$O$_7$, indicating unexpected Fermi surface changes during critical fluctuations.

Contribution

It provides new insights into the tunneling behavior and Fermi surface evolution of Sr$_3$Ru$_2$O$_7$ near its quantum critical point, distinct from traditional quantum oscillations.

Findings

Unusual oscillation in tunneling magnetoresistance observed.

Tunneling spectra change sharply below 2 mV near the transition.

Fermi surface undergoes surprising modifications during critical fluctuations.

Abstract

We performed single electron tunneling measurements on bilayer ruthenate Sr$_3$Ru$_2$O$_7$. We observe an unusual oscillation in tunneling magnetoresistance near the metamagnetic quantum phase transition at temperatures below 7 K. The characteristic features of this oscillation suggest that it is unrelated to traditional quantum oscillations caused by orbit quantization. In addition, tunneling spectra are found to change sharply in the low bias voltage range of $V$ $<$ 2mV near the transition field. These observations reveal that the Fermi surface of Sr$_3$Ru$_2$O$_7$ changes in a surprising way as the system undergoes strong critical fluctuations.