Spin-glass state of (Nd,La)0.5Sr1.5MnO4

We studied the low-temperature magnetic properties of single-crystal (Nd1-xLax)0.5Sr1.5MnO4 using ac and dc susceptibility, and magnetization measurements. From this study, we found that Nd-doped samples showed the sign of a different magnetic state below 20 K. A peak in the ac susceptibility signaling the state shows a strong frequency dependence, indicative of the metastable nature of the transition. This metastable nature of the transition is also borne out by the nonzero isothermal remnant magnetization and the difference in the peak temperatures determined from ac and dc susceptibility. A further evidence for this conclusion comes from the absence of magnetic peaks at low temperature in our neutron-diffraction pattern.