Magnetic properties of geometrically frustrated SrGd2O4

A study of the magnetic properties of the frustrated rare-earth oxide SrGd2O4 has been completed using bulk property measurements of magnetization, susceptibility, and specific heat on single-crystal samples. Two zero-field phase transitions have been identified at 2.73 and 0.48 K. For the field H, applied along the a and b axes, a single boundary is identified that delineates the transition from a low-field, low-temperature magnetically ordered regime to a high-field, high-temperature paramagnetic phase. Several field-induced transitions, however, have been observed with H parallel to c. The measurements have been used to map out the magnetic phase diagram of SrGd2O4, suggesting that it is a complex system with several competing magnetic interactions. The low-temperature magnetic behavior of SrGd2O4 is very different compared to the other SrL2O4 (L = Lanthanide) compounds studied so far, even though all of the SrL2O4 compounds are isostructural, with the magnetic ions forming a low-dimensional lattice of zigzag chains that run along the c axis. The differences are likely to be due to the fact that in the ground state Gd3+ has zero orbital angular momentum and therefore the spin-orbit interactions, which are crucial for other SrL2O4 compounds, can largely be neglected. Instead, given the relatively short Gd3+-Gd3+ distances in SrGd2O4, dipolar interactions must be taken into account for this antiferromagnet alongside the Heisenberg exchange terms.