Eu2+-Eu3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies

Bartlomiej Wiendlocha, Sunphil Kim, Yeseul Lee, Bin He, Gloria Lehr, Mercouri G. Kanatzidis, Donald T. Morelli, Joseph P. Heremans

Research output: Contribution to journalArticle

Abstract

The Eu atoms in Pb1-xEuxSe have long been assumed to be divalent. We show that p-type doping of this magnetic semiconductor alloy with Na can modify the effective Eu valence: a mixed, Eu2+-Eu3+ state appears in Pb1-x-yEuxNaySe at particular values of y. Magnetization, carrier concentration, resistivity, and thermopower of Pb1-x-yEuxNaySe are reported for a number of samples with different x and y. A pronounced increase in thermopower at a given carrier concentration was identified and attributed to the presence of enhanced ionized impurity scattering. A strong decrease in the hole concentration is observed in Pb1-yNaySe when Eu is added to the system, which we attribute to a Eu2+-Eu3+ self-ionization process. This is evidenced by magnetization measurements, which reveal a significant reduction of the magnetic moment of Pb1-xEuxSe upon alloying with Na. Further, a deviation of magnetization from a purely paramagnetic state, described by a Brillouin function, identifies antiferromagnetic interactions between the nearest-neighbor Eu atoms: a value of Jex/kB = -0.35 K was found for the exchange coupling parameter. The conclusion of a Eu2+-Eu3+ self-ionization process being in effect is supported further by the electronic structure calculations, which show that an instability of the 4f7 configuration of the Eu2+ ion appears with Na doping. Schematically, it was found that the Eu 4f levels form states near enough to the Fermi energy that hole doping can lower the Fermi energy and trigger a reconfiguration of a 4f electronic shell.

LanguageEnglish (US)
Pages9606-9616
Number of pages11
JournalPhysical Chemistry Chemical Physics
Volume19
Issue number14
DOIs
StatePublished - 2017

Profile

Magnetic structure
Electronic structure
Magnetization
Thermoelectric power
Doping (additives)
electronic structure
Fermi level
valence
magnetization
Ionization
Carrier concentration
ionization
Magnetic semiconductors
Hole concentration
Atoms
Exchange coupling
Magnetic moments
Alloying
alloying
atoms

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Wiendlocha, B., Kim, S., Lee, Y., He, B., Lehr, G., Kanatzidis, M. G., ... Heremans, J. P. (2017). Eu2+-Eu3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies. Physical Chemistry Chemical Physics, 19(14), 9606-9616. DOI: 10.1039/c7cp00358g

Eu2+-Eu3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies. / Wiendlocha, Bartlomiej; Kim, Sunphil; Lee, Yeseul; He, Bin; Lehr, Gloria; Kanatzidis, Mercouri G.; Morelli, Donald T.; Heremans, Joseph P.

In: Physical Chemistry Chemical Physics, Vol. 19, No. 14, 2017, p. 9606-9616.

Research output: Contribution to journalArticle

Wiendlocha, Bartlomiej ; Kim, Sunphil ; Lee, Yeseul ; He, Bin ; Lehr, Gloria ; Kanatzidis, Mercouri G. ; Morelli, Donald T. ; Heremans, Joseph P./ Eu2+-Eu3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies. In: Physical Chemistry Chemical Physics. 2017 ; Vol. 19, No. 14. pp. 9606-9616
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