Superconductivity in La<i>T</i><sub><i>M</i></sub>BN and La<sub>3</sub><i>T</i><sub><i>M</i>2</sub>B<sub>2</sub>N<sub>3</sub> (<i>T</i><sub><i>M</i></sub> = Transition Metal) Synthesized under High Pressure


Various layered boronitrides (LaN)<sub><i>n</i></sub>(<i>T</i><sub><i>M</i>2</sub>B<sub>2</sub>) (<i>T</i><sub><i>M</i></sub> = transition metal; <i>n</i> = 2, 3) have been prepared using a high-pressure synthesis technique in which an inverse α-PbO-type <i>T</i><sub><i>M</i>2</sub>B<sub>2</sub> layer is separated by two or three rock salt-type LaN layers and these layers are connected through linear (BN) units. The electronic states of the distinguishing (BN) unit and intermediate rock salt-type LaN layer are discussed on the basis of density functional theory calculations. Bulk superconductivity has been found in LaNiBN (<i>T</i><sub>c</sub> ≈ 4.1 K), CaNiBN (<i>T</i><sub>c</sub> ≈ 2.2 K), and LaPtBN (<i>T</i><sub>c</sub> ≈ 6.7 K), where the Fermi level <i>E</i><sub>F</sub> is located in the bands composed of the <i>T</i><sub><i>M</i></sub>(d)–B­(2p) antibonding state and the main <i>T</i><sub><i>M</i></sub>(d) band resides well below <i>E</i><sub>F</sub>. The non-superconductive <i>T</i><sub><i>M</i></sub>-based compounds exhibit Pauli paramagnetic behavior, in which the highly itinerant nature of the electrons caused by strong <i>T</i><sub><i>M</i></sub>(d)–B­(2p) covalent bonding suppresses the long-range magnetic ordering

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oai:figshare.com:article/2551762Last time updated on 2/12/2018

This paper was published in FigShare.

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