Negative differential resistance in single crystal La_{2}CuO_{4} at low   temperature
  A current-controlled negative differential resistance has been revealed in the I-V characteristics of single crystal La$_{2}$CuO$_{4+\delta}$ in the low temperature region. The non-linear behavior of conductivity is accompanied by a transition from positive to negative magnetoresistance when the current is growing. Possible reasons for the effect observed are discussed. 
B. I. Belevtsev, N. V. Dalakova