Evidence of unconventional superconductivity in the Ni-doped NbB2 system

Autor(es)

Renosto, S. T. ^[1] ; Lang, R. ^[2] ; Diez, E. ^[1] ; Correa, L. E. ^[3] ; da Luz, M. S. ^[4] ; Fisk, Z. ^[5] ; Machado, A. J. S. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Salamanca, Dept Fis Fundamental, Nanolab, Grp Nanotecnol, E-37008 Salamanca - Spain

^[2] Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos - Brazil

^[3] Univ Sao Paulo, Dept Mat, BR-12602810 Lorena - Brazil

^[4] Univ Fed Triangulo Mineiro, BR-38066200 Uberaba - Brazil

^[5] Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 - USA

• Tipo de documento: Artigo Científico
• Fonte: Journal of Alloys and Compounds; v. 787, p. 414-422, MAY 30 2019.
• Citações Web of Science: 1

Resumo

In this paper, a comprehensive study of the effects of Ni-doping on structural, electrical, thermal and magnetic properties of the NbB2 is presented. Low amounts (<= 10%) of Ni substitution on Nb sites cause structural distortions and induce drastic changes in the physical properties, such as the emergence of a bulk superconducting state with anomalous behaviors in the critical fields (lower and upper) and in the specific heat. Ni-doping at the 9 at.% level, for instance, is able to increase the critical temperature (T-c) in stoichiometric NbB2 (<1.3 K) to approximately 6.0 K. Bulk superconductivity is confirmed by magnetization, electronic transport, and specific heat measurements. Both H-c1 and H-c2 critical fields exhibit a linear dependence with reduced temperature (T/T-c), and the specific heat deviates remarkably from the conventional exponential temperature dependence of the single-band BCS theory. These findings suggest multiband superconductivity in the composition range from 0.01 <= x <= 0.10 (Nb1-xNixB2). (C) 2019 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 18/08819-2 - Crescimento de monocristais de dicalcogênios de protótipo CdI2 e investigação de propriedades supercondutoras
• Beneficiário: Lucas Eduardo Corrêa
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 14/25235-3 - Estudo da Estrutura de Defeitos e sua influência nas Propriedades Fonônicas e Eletrônicas nos compostos Supercondutores do tipo M1-xVxB2
• Beneficiário: Sérgio Tuan Renosto
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado