Antiferromagnetic spin resonance and magnetic phase diagram of deuterated κ-(BEDT-TTF)2Cu[N(CN)2]Br

The antiferromagnetic phase of a deuterated salt of κ-(BEDT-TTF)2Cu[NCN)2]Br is studied by magnetic resonance and resistivity measurements. When the sample is cooled rapidly, antiferromagnetic spin resonance (AFMR) signals are found below 6–8 K. With the aid of resistivity measurements under pressure, the magnetic phase diagram in the weak pressure region is obtained. The cooling-rate and temperature dependence of the APMR signals are explained in terms of a reentrant superconductivity found close to ambient pressure