Interplay among spin, orbital, and lattice degrees of freedom in a frustrated spinel Mn₃O₄

We have investigated magnetic-field (Hâ̂¥[100]) effect on a spin-frustrated tetragonally distorted spinel Mn₃O₄ by measurements of magnetization, dielectric constant, and strain as well as synchrotron x-ray and neutron diffraction. In two low-temperature phases below 40 K, long-wavelength lattice modulations coupled with magnetic order have been confirmed, revealing spin-lattice coupling caused by the exchange striction in the geometrically frustrated Mn3⁺ spin moments on the distorted pyrochlore lattice. A magnetic-field-induced phase transition has been found at low temperatures, which involves an abrupt change in both structural and magnetic configurations. The magnetostructural phase transition by the application of a magnetic field Hâ̂¥[100] is discussed in terms of interplay among spin, orbital, and lattice degrees of freedom.