Field-induced first-order magnetic phase transition in an intermetallic compound Nd<SUB>7</SUB>Rh<SUB>3</SUB>: evidence for kinetic hindrance, phase coexistence, and percolative electrical conduction

The compound Nd<SUB>7</SUB>Rh<SUB>3</SUB>, crystallizing in the Th<SUB>7</SUB>Fe<SUB>3</SUB>-type hexagonal structure, was previously known to exhibit two magnetic transitions, one at 32 K and the other at 10 K (in a zero magnetic field). Here we report the existence of a field-induced first-order antiferromagnetic-to-ferromagnetic transition at 1.8 K in this compound. On the basis of the measurements of isothermal magnetization and magnetoresistance, we provide evidence for the occurrence of "kinetic hindrance", proposed in the recent literature, resulting in phase coexistence ("supercooled" ferromagnetic+antiferromagnetic) and percolative electrical conduction in this stoichiometric intermetallic compound. A point of emphasis, as inferred from ac susceptibility data, is that such a coexisting phase is different from spin glasses thereby clarifying a question raised in the field of 'phase separation'