• Koughnet, K. Van
• Holmes-Hewett, W. F.
• Buckley, R. G.
• Ruck, B. J.
• Trewick, E. X. M.
• Trodahl, H. J.
• Miller, J. D.

Abstract

<jats:title>Abstract</jats:title><jats:p>We investigate the previously observed superconductivity in ferromagnetic SmN in the context of the breakdown of order between two magnetic phases. Nitrogen vacancy doped SmN<jats:inline-formula><jats:alternatives><jats:tex-math>_{1- }</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow /><mml:mrow><mml:mn>1</mml:mn><mml:mo>-</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:math></jats:alternatives></jats:inline-formula> is a semiconductor which lies in the intermediary between ferromagnetic SmN and anti-ferromagnetic Sm. Optical data reported here corroborate the prediction that electrical transport is mediated by Sm 4<jats:italic>f</jats:italic> defect states, and electrical transport measurements characterise the metal-insulator transition over the doping range. Our measurements show that the superconducting state in nitrogen vacancy doped <jats:inline-formula><jats:alternatives><jats:tex-math>{SmN}_{1- }</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>SmN</mml:mtext><mml:mrow><mml:mn>1</mml:mn><mml:mo>-</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:math></jats:alternatives></jats:inline-formula> is the most robust near the breakdown of magnetic order, and indicate the location of a quantum critical point. Furthermore we provide additional evidence that the superconducting state is formed from majority spin electrons and thus of unconventional S = 1 type.</jats:p>

Topics

• impedance spectroscopy
• phase
• semiconductor
• Nitrogen
• vacancy
• superconductivity
• superconductivity