Abstract
We have measured the dc magnetization of three high-quality single crystals of with a SQUID magnetometer down to in magnetic fields below 2 mT. With in the direction we find a double superconducting transition, while for we observe only one. At lower temperatures the temperature dependence of the magnetization follows power laws indicating unconventional behavior for the penetration depth. Below 20 mK a steep diamagnetic drop occurs, coinciding with the specific heat anomaly which we found earlier at 18 mK, pointing to static antiferromagnetic order.
- Received 6 May 1998
DOI:https://doi.org/10.1103/PhysRevLett.82.2378
©1999 American Physical Society