On the Magnetic Properties of a CrBr3 Single Crystal

Magnetic properties of single crystals of CrBr 3 have been measured with a magnetic balance and also with a torque magnetometer. The ferromagnetic Curie point has been found to be 37°K from the temperature dependences of magnetization and of torque. Based on the data of the magnetic susceptibility above the Curie point, the paramagnetic Curie point θ p , Curie constant C M and the effective Bohr magneton number have been determined to be 47°K, 1.84 and 3.85 µ B respectively. From the saturation magnetization at 42°K, the moment of chromium ion is estimated to be 3 µ B , coinciding with the spin moment obtained from the susceptibility measurement above the Curie temperature. Direction of easy magnetization lies along the c -axis of the hexagonal lattice, and the second order and the fourth order anisotropy constants are estimated to be K 1 =-5.08×10 5 and K 2 =0.65×10 5 erg/cc respectively. In the present results, there is found a small deviation in the torque curves from simple sinusoidal form, L = K sin 2θ, which is discussed on the basis of the higher order term of magnetic anisotropy in the high field strength range and also of the domain-theoretical consideration in the low field strength range.