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 || 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 SrLn2O4 (Ln = Lanthanide) compounds, even though all of the SrLn2O4
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
SrLn2O4 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.Comment: 10 pages, 9 figure
