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Title: Effect of Sr doping on the magnetic exchange interactions in manganites of type L a 1 - x S r x M n y A 1 - y O 3 ( A = Ga , Ti ; 0.1 y 1 )

Strontium doping transforms manganites of type La 1 - x Sr x Mn O 3 from an insulating antiferromagnet ( x = 0 ) to a metallic ferromagnet ( x > 0.16 ) due to the induced charge carriers (holes). We employed neutron scattering experiments in order to investigate the effect of Sr doping on a tailor-made compound of composition La 0.7 S r 0.3 M n 0.1 Ti 0.3 G a 0.6 O 3 . By the simultaneous doping with S r 2 + and Ti 4 + ions, the compound remains in the insulating state so that the magnetic interactions for large Sr doping can be studied in the absence of charge carriers. At T C = 215 K , there is a first-order reconstructive phase transition from the trigonal R - 3 c structure to the orthorhombic Pnma structure via an intermediate virtual configuration described by the common monoclinic subgroup P2 1 / c . The magnetic excitations associated with Mn 3 + dimers give evidence for two different nearest-neighbor ferromagnetic exchange interactions, in contrast to the undoped compound LaM n y A 1 - y O 3 where both ferromagnetic and antiferromagnetic interactions are present.more » Furthemore, the doping-induced changes of the exchange coupling originates from different Mn-O-Mn bond angles determined by neutron diffraction. The large fourth-nearest-neighbor interaction found for metallic manganites is absent in the insulating state. Here, we argue that the Ruderman-Kittel-Kasuya-Yosida interaction reasonably accounts for all the exchange couplings derived from the spin-wave dispersion in metallic manganites.« less
 [1] ;  [2] ;  [3] ;  [4]
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab of Neutron Scattering and Imaging; SwissNeutronics AG, Klingnau (Switzerland)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  3. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. for Scientific Developments and Novel Materials
  4. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab of Neutron Scattering and Imaging
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 10; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1347051