抄録
A single-crystal neutron diffraction study was made on the structural and magnetic phase transitions of the distorted-triangular-lattice Ising-like antiferromagnet RbCoBr3. Below the structural phase transition point, Tst1=90 K, the chemical unit cell was found to be enlarged to (\\sqrt3a,\\sqrt3a,c). The temperature dependence of the (1,1,1) magnetic Bragg peak of this crystal shows absence of the intermediate ‘partial disorder’ phase, which is known to appear between the paramagnetic and ferrimagnetic phases of the typical Ising-like triangular-lattice antiferromagnets CsCoCl3 and CsCoBr3. The present result, that the partial disorder phase vanishes, is due to the release of spin frustration.
