Unusual Nernst effect suggestive of time-reversal violation in the   striped cuprate La$_{2-x}$Ba$_x$CuO$_4$
  The striped cuprate La$_{2-x}$Ba$_x$CuO$_4$ ($x=\frac18)$ undergoes several transitions below the charge-ordering temperature $T_{co}$ = 54 K. From Nernst experiments, we find that, below $T_{co}$, there exists a large, anomalous Nernst signal $e_{N,even}(H,T)$ that is symmetric in field $H$, and remains finite as $H\to 0$. The time-reversal violating signal suggests that, below $T_{co}$, vortices of one sign are spontaneously created to relieve interlayer phase frustration. 
Lu Li, N. Alidoust, J. M. Tranquada, G. D. Gu, and N. P. Ong
cond-mat.supr-con cond-mat.str-el