The effect of chemical substitution on the ground state of the geometrically frustrated antiferromagnet CsCrF$_4$ has been investigated through a neutron powder diffraction experiment. Magnetic Fe-substituted CsCr$_{ 0.94}$Fe$_{ 0.06}$F$_{ 4}$ and nonmagnetic Al-substituted CsCr$_{ 0.98}$Al$_{ 0.02}$F$_{ 4}$ samples are measured, and magnetic Bragg peaks are clearly observed in both samples. Magnetic structure analysis revealed a 120$^{ \circ}$ structure having a magnetic propagation vector $\mathbf{ k}_{ \rm mag}=(0,0,1/2)$ in CsCr$_{ 0.94}$Fe$_{ 0.06}$F$_{ 4}$. For CsCr$_{ 0.98}$Al$_{ 0.02}$F$_{ 4}$, a quasi-120$^{ \circ}$ structure having $\mathbf{ k}_{ \rm mag}=(1/2,0,1/2)$ is formed. It is notable that the identified magnetic structure in CsCr$_{ 0.94}$Fe$_{ 0.06}$F$_{ 4}$ belongs to a different phase of ground states from those in CsCr$_{ 0.98}$Al$_{ 0.02}$F$_{ 4}$ and the parent CsCrF$_{ 4}$. These results suggest that the Fe-substitution strongly influences the ground state of CsCrF$_{ 4}$.
Categories: cond-mat.str-el