Muon Spin Relaxation Studies of Magnetic-Field-Induced Effects in High-$T_c$ Superconductors

Abstract

Muon spin relaxation ($\hat{I}¼$SR) measurements in high transverse magnetic fields ($\parallel \hat{c}$) revealed strong field-induced quasi-static magnetism in the underdoped and Eu doped (La,Sr)${}_2$CuO${}_4$ and La${}_{1.875}$Ba${}_{0.125}$CuO${}_4$, existing well above $T_c$ and $T_N$. The susceptibility-counterpart of Cu spin polarization, derived from the muon spin relaxation rate, exhibits a divergent behavior towards $T\sim 25$ K. No field-induced magnetism was detected in overdoped La${}_{1.81}$Sr${}_{0.19}$CuO${}_4$, optimally doped Bi2212, and Zn-doped YBa${}_2$Cu${}_3$O${}_7$.

4 pages, 4 color figures