Evidence for a field-driven transition in YBa 2Cu 3O 7−δ single crystal

Abstract

Isothermal global magnetic measurements in a detwinned YBa 2Cu 3O 7−δ single crystal revealed an abrupt change in the slope of the increasing part of the virgin magnetization curves ( M( H)). The temperature dependence of the magnetic field H 3 at which this feature occurs decreases with temperature from 5 up to 40 K and after for T > 40 K increases. For temperatures near the line defined by the points of the fishtail peak, the feature is hard to discern.