Magnetic phase transitions in Rb/sub 2/MnC1/sub 4/ studied by neutron scattering and spectroscopic measurements in the millimeter wave range

By magnetic resonance in the mm-wave range combined with neutron scat tering, we have studied the magnetic phase transitions in Rb/sub 2/MnC1/sub 4/ and obtained new results, contradicting the generally accepted conceptions about uniaxial antiferromagnets with weak anisotropy.