Above-room-temperature coupling between ferroelastic domains and magnetism in an organic-inorganic hybrid: CsCu(HCOO)2Cl

Coupling between ferroelastic domains and magnetism (CFM) is usually observed in ferromagnetic phases where an easily magnetized direction can change with the movement of ferroelastic domains. Organic-inorganic hybrids (OIHs) are expected to enhance the coupling due to their low elastic modules. However, it is challenging to find CFM above room temperature in OIHs since the magnetic orderings are generally at low temperatures. The occurrence of CFM without magnetic ordering remains a question. Here, we report an interesting OIH: $\mathrm{CsCu}{(\mathrm{HCOO})}₂\mathrm{Cl}$, where canted antiferromagnetic and ferroelastic ordering occur at 32 and 331 K, respectively. Induced by Cu dimers, $\mathrm{CsCu}{(\mathrm{HCOO})}₂\mathrm{Cl}$ shows large magnetic anisotropy at room temperature, the strength of which is twice that below 32 K. It is an example of an OIH showing that ferroelastic domains can couple with magnetism above room temperature. Moreover, our findings present a way to realize room-temperature CFM in OIHs and enhance our understanding of CFM.