Closing the Pseudogap by Zeeman Splitting in Bi_2Sr_2CaCu_2O_8+y at High Magnetic Fields

TL;DR

This study uses high magnetic fields to investigate the pseudogap in Bi-2212, revealing that Zeeman splitting can close the pseudogap and highlighting the dominant role of spin effects over orbital effects in its formation.

Contribution

The paper demonstrates that the pseudogap in Bi-2212 can be closed by Zeeman splitting at high magnetic fields, establishing a direct relation between the pseudogap closing field and temperature.

Findings

Pseudogap is closed by Zeeman energy at high fields.

Pseudogap closing field and $T^{igstar}$ are related via Zeeman scaling.

Spin effects dominate over orbital effects in pseudogap formation.

Abstract

Interlayer tunneling resistivity is used to probe the low-energy density-of-states (DOS) depletion due to the pseudogap in the normal state of Bi$_2$Sr$_2$CaCu$_2$O$_{8+y}$. Measurements up to 60 T reveal that a field that restores DOS to its ungapped state shows strikingly different temperature and doping dependencies from the characteristic fields of the superconducting state. The pseudogap closing field and the pseudogap temperature $T^{\star}$ evaluated independently are related through a simple Zeeman energy scaling. These findings indicate a predominant role of spins over the orbital effects in the formation of the pseudogap.