Magnetic susceptibility of the V15 nanocluster in megagauss magnetic fields

The low-temperature behavior of the magnetic susceptibility of the V15 low-spin cluster in ultrastrong magnetic fields of up to 550 T was studied. Ultrastrong magnetic fields were generated by an MK-1 magnetic explosion generator. Anomalies in the susceptibility were found to exist in fields B1=200 T and B2=350 T. It is concluded that these anomalies indicate the initial phase of a field-induced transformation of the cluster magnetic structure from quasi-ferrimagnetic to ferromagnetic. This transformation occurs by discrete quantum jumps at low temperatures. The experimental data are compared with theory.