Evaluation of field-induced magnetic moments in the spin-1/2 antiferromagnetic trimerized chain compound Cu3(P2O6OD)2

We report on our evaluation of field-induced magnetic moments in the paramagnetic state of the spin- 1/2 antiferromagnetic trimerized (J1 − J2 − J2) chain compound Cu3(P2O6OD)2 with J1 = 111K and J2 = 30K
[M. Hase et al., Phys. Rev. B 76, 064431 (2007)]. Magnetic reflections with integer indices, generated by fieldinduced magnetic moments, were observed at neutron-diffraction experiments performed in an applied magnetic field, and we evaluated the magnitudes of the moments to be M1 = 0.43(2)μB/Cu and M2 = 0.013(10)μB/Cu on the two crystallographic Cu2+ (Cu1 and Cu2) sites, respectively, at 6 T and 1.6 K. The resulting ratio M2/M1 = 0.03(2) is in good agreement with the theoretical value for the ratio of the magnetization at the two sites. We thus conclude that for this well-understood spin system (which has the advantage of being amenable to detailed theoretical calculations) the extracted field-induced magnetic moments reproduce the correct information on the magnetization. Our result leads us to believe that we can precisely evaluate exchange interactions in paramagnets with multiple exchange interactions and multiple crystallographic magnetic-ion sites
by using field-induced magnetic moments in combination with macroscopic physical quantities. This idea is expected to be applicable to a wide variety of quantum and frustrated magnets without long-range order.