Tuning of the dimensionality in an S = 1 / 2 spatially anisotropic square lattice antiferromagnet [ ( CH 3 ) 2 NH 2 ] Cu ( HCOO ) 2 ( NO 3 )

In this paper, magnetic properties of formate perovskite $[{({\mathrm{CH}}₃)}₂{\mathrm{NH}}₂]\mathrm{Cu}{(\mathrm{HCOO})}₂({\mathrm{NO}}₃)$ (DMACu-${\mathrm{NO}}₃$) single crystals are reported. ${\mathrm{Cu}}²⁺$ ions feature an $S=1/2$ rectangular lattice in the $bc$ plane, which can be considered as a weakly frustrated spatially anisotropic square lattice. Upon cooling, a canted antiferromagnetic order is developed below ${T}_{\mathrm{N}}=21.5\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ with an easy-plane anisotropy perpendicular to the $a$ axis. When the magnetic field is applied along the $b$ axis, a field-induced transition appears around 0.05 T at 2 K. In comparison with the one-dimensional chain antiferromagnet $[{({\mathrm{CH}}₃)}₂{\mathrm{NH}}₂]\mathrm{Cu}{(\mathrm{HCOO})}₃$, the dimensionality switch in DMACu-${\mathrm{NO}}₃$ is originated from the orbital reorientation on half Cu ions after replacing 1/3 HCOO ligands with ${\mathrm{NO}}₃$ linkers.