Campus de Excelencia InterncionalCampus of International Excellence

Valence Fluctuations and Unusual Correlations in Superconducting Pb1 xTlxTe

Fechas celebración

Desde el 19-04-2018 hasta el 19-04-2018

Hora Celebración

12.00 H

Lugar Celebración

Dpto. Física de la Materia Condensada, Facutad de Ciencias, Módulo 3, Sala Seminario (5ª planta)

Descripción

Abstract:  

The narrow-band semiconductor PbTe superconducts with a Tc an order of magnitude greater than comparable low-density metals, but only when it is doped with valence-skipping elements. There is strong experimental evidence that upon hole-doping PbTe with Tl the onset of superconductivity occurs as the chemical potential is tuned to a point of degeneracy of the Tl 1+ and 3+ valences. At these compositions the Tl dopants can dynamically skip valence by filling and emptying their 6s shell of two electrons simultaneously, naturally raising the question of whether Tl dopants can act as a negative U center to produce the enhanced superconductivity seen in this compound.

 

Here we present a study of the quantum oscillations, electrical transport and specific heat of hole-doped PbTe in which we use a series of non-superconducting, non-valence skipping Na doped samples as a control system for the Tl doped series described above. We identify the presence of an unusual 2e resonant impurity state that is unique to the superconducting portion of the Tl series, and appears to be enhancing, or even introducing, the pairing interaction in this material. This realization of a pairing interaction that is introduced extrinsically to a host material could guide the design of improved superconducting materials.

 

cid:11516B45-23FD-4C4E-8D2F-D1F4A0DFC39D

Más información: http://www.ifimac.uam.es/category/seminars/

 

Dear all:

 

A new IFIMAC Conference will  take place on Thursday; April 19th at the  Condensed Matter Physics Center (IFIMAC )

You will find all the information below.

 

WHEN: Thursday; April 19th (2018); 12.00 h

WHERE: Dpto. Física de la Materia Condensada, Facultad Ciencias, Module 3, Seminar Room (5th Floor)

 

SPEAKER: Phil Walmsley (Stanford University)

 

TITLE: Valence Fluctuations and Unusual Correlations in  Superconducting Pb1-xTlxTe

 

ABSTRACT:

The narrow-band semiconductor PbTe superconducts with a Tc an order of magnitude greater than comparable low-density metals, but only when it is doped with valence-skipping elements. There is strong experimental evidence that upon hole-doping PbTe with Tl the onset of superconductivity occurs as the chemical potential is tuned to a point of degeneracy of the Tl 1+ and 3+ valences. At these compositions the Tl dopants can dynamically skip valence by filling and emptying their 6s shell of two electrons simultaneously, naturally raising the question of whether Tl dopants can act as a negative U center to produce the enhanced superconductivity seen in this compound.

 

Here we present a study of the quantum oscillations, electrical transport and specific heat of hole-doped PbTe in which we use a series of non-superconducting, non-valence skipping Na doped samples as a control system for the Tl doped series described above. We identify the presence of an unusual 2e resonant impurity state that is unique to the superconducting portion of the Tl series, and appears to be enhancing, or even introducing, the pairing interaction in this material. This realization of a pairing interaction that is introduced extrinsically to a host material could guide the design of improved superconducting materials.

 

More information: http://www.ifimac.uam.es/category/seminars/

 

 

 

 

--

Almudena Conde Angulo

Project Manager

Condensed Matter Physics Center (IFIMAC)

Universidad Autónoma de Madrid

Phone: +34 914972433

e-mail: ifimac@uam.es 

 

 

 

 

 

 

Agentes y colaboradores

  • Universidad Autónoma de Madrid
  • CSIC
  • ASEYACOVI
  • ACENOMA
  • AICA
  • Centro de Microanálisis de Materiales (CMAM)
  • Centro de Investigación en Física de la Materia Condensada (IFIMAC)
  • CBMSO - Centro de Biología Molecular Severo Ochoa
  • CIAL - Centro de Investigación en Ciencias de la Alimentación
  • CNB - Centro Nacional de Biotecnología 
  • Centro de Iniciativas Emprendedoras (CIADE)
  • Cámara de Madrid
  • FEMAN
  • Fundación Universitaria Autónoma de Madrid
  • ICMAT - Instituto de Ciencias Matemáticas
  • ICMM - Instituto de Ciencia de Materiales de Madrid
  • ICP - Instituto de Catálisis y Petroquímica
  • ICV - Instituto de Cerámica y Vidrio
  • IFT - Instituto de FísicaTeórica
  • IIBM - Instituto de Investigaciones Biomédicas Alberto Sols
  • IMDEA - Alimentación
  • IMDEA - Nanociencia
  • IMM - Instituto de Microelectrónica de Madrid
  • InNorMadrid
  • Parque Científico de Madrid
  • Oficina de Transferencia de Resultados de la Investigación (OTRI) de la UAM
  • Facultad de Ciencias
  • Facultad de Ciencias Económicas y Empresariales
  • Facultad de Derecho
  • Facultad de Filosofía y Letras
  • Facultad de Medicina
  • Facultad de Formación de Profesorado y Educación
  • Facultad de Psicología
  • Escuela Politécnica Superior
Proyecto realizado con ayudas concedidas por el Ministerio de Economía y Competitividad / EXPEDIENTE: CEI10-1-0009 CEI UAM+CSIC: INNOCAMPUS 2010 Proyecto financiado por el Ministerio de Educación, Cultura y Deporte, y el Ministerio de Economía y Competitividad en el marco del Programa Campus de Excelencia Internacional/ EXPEDIENTE: CEI10-1-0009 CEI UAM+CSIC: INNOCAMPUS 2010