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Title: Hole doping and pressure effects on the II-II-V-based diluted magnetic semiconductor ( B a 1 - x K x ) ( Z n 1 - y M n y ) 2 A s 2

We investigate doping- and pressure-induced changes in the electronic state of Mn 3d and As 4p orbitals in II-II-V based diluted magnetic semiconductor (Ba 1-x,K x)(Zn 1-y,Mn y) 2As 2 to shed light into the mechanism of indirect exchange interactions leading to high ferromagnetic ordering temperature (T c = 230 K in optimally doped samples). A suite of x-ray spectroscopy experiments (emission, absorption and dichroism) show that the emergence, and further enhancement of ferromagnetic interactions with increased hole doping into the As 4p band is accompanied by a decrease in local 3d spin density at Mn sites. This is a result of increasing Mn 3d - As 4p hybridization with hole doping which enhances indirect exchange interactions between Mn dopants and gives rise to induced magnetic polarization in As 4p states. On the contrary, application of pressure suppresses exchange interactions. While Mn Kβ emission spectra show a weak response of 3d state to pressure, clear As 4p band broadening (hole delocalization) is observed under pressure ultimately leading to loss of ferromagnetism concomitant with a semiconductor to metal transition. The pressure response of As 4p and Mn 3d states is intimately connected with the evolution of the As-As interlayer distance andmore » the geometry of the MnAs 4 tetrahedral units, which we probed with X-ray diffraction. Our results indicate that hole doping increases the degree of covalency between the anion (As) p states and cation (Mn) d states in the MnA s4 tetrahedron, a crucial ingredient to promote indirect exchange interactions between Mn dopants and high T c ferromagnetism. As a result, the instability of ferromagnetism and semiconducting state against pressure is mainly dictated by delocalization of anion p states.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5] ;  [5] ;  [5] ;  [6] ;  [4] ;  [6] ;  [7]
  1. Chinese Academy of Sciences (CAS), Beijing (China); Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Chinese Academy of Sciences (CAS), Beijing (China)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Brazilian Synchrotron Light Lab. (LNLS), Campinas, SP (Brazil)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
  5. Carnegie Inst. of Washington, Argonne, IL (United States)
  6. Carnegie Inst. of Washington, Argonne, IL (United States); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China)
  7. Chinese Academy of Sciences (CAS), Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Univ. of Chinese Academy of Sciences, Beijing (China)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FG02-99ER45775; NA0001974
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 9; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1373594
Alternate Identifier(s):
OSTI ID: 1346761