Magnetic phase transitions induced by the field H = (<i>H</i> <i>x</i>, <i>H</i> <i>y</i>, 0) in dysprosium orthoferrite

Spin-flip transitions induced by a magnetic field oriented in the ab plane of a crystal are investigated in dysprosium orthoferrite. A tilted field H = (Hx, Hy, 0) is shown to induce a first-order phase transition between the Γ124-type states with a spatial orientation of the ferro- and antiferromagnetism vectors. The magnetic H-T phase diagrams of DyFeO3 with different orientations of the field in the ab plane are constructed. It is found that the orientation of H at an angle of α* ≈ 62° to the a-axis is such that the high-temperature (Γ ′124) and low-temperature (Γ ″124) phases at the Morin point are energetically equivalent in the entire interval of investigated magnetic fields. The magnetic field H = (Hx, Hy. 0) induces in the temperature interval T &amp;lt; TM a phase transition between the Γ124-type states only for α &amp;gt; α*, and in the temperature region T &amp;gt; TM, only for α &amp;lt; α*.

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