As a part of an extensive study of the new geometric frustration series M2(OH)3X (M: 3d magnetic ion; X: halogen ion) on deformed pyrochlore lattice we have investigated in detail the magnetism of Co2(OH)3Cl1-xBrx, in which the magnetic state was found to be very sensitive to the anion substitution. Co2(OH)3Br was found to undergo antiferromagnetic transitions at TN1=6.2 K and TN2=4.8 K, respectively, which are contrasting as compared to the partial ferromagnetic state in Co2(OH)3Cl. Muon spin precession was observed with additional fast relaxation below TN1, implying coexisting spin-fluctuation. Meanwhile, the partially substituted Co2(OH)3Cl1-xBrx transforms from ferromagnetic to antiferromagnetic by increasing the x ratio. The present work presents a unique system to investigate the critical role of the tetrahedral distortion in geometric frustration.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering