Phase diagram of MoB2. Insert is the Diamond Anvil Cell (left) and Atomic displacements of the lowest acoustic mode of MoB2 (right). (IMAGE)
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The superconducting phase diagram of MoB2 as a function of the pressure is summarized in the Figure. Utilizing Diamond Anvil Cell (DAC) (left), it can be seen that the superconducting state emerges around 20 GPa, and then the Tc increases further with applied pressure, and beyond the structure-transition pressure (Pc ∼ 70 GPa) the growth of Tc slows down. The Tc of MoB2 rises to as high as ∼32 K at a pressure of 109.7 GPa and still does not exhibit the trend of saturation. Further theoretical calculations suggest that the out-of-plane phonon mode of Mo atoms couples strongly with Mo d electrons near EF (right). These results reveal the study of superconducting mechanism in high-pressure α-MoB2 sheds light on exploring of new phonon-mediated high-Tc superconductors in transition metal borides.
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