Jiangang He

Publications (3)7.38 Total impact

• Article: Structural transitions and transport-half-metallic ferromagnetism in LaMnO3 at elevated pressure

  Jiangang He, Ming-Xing Chen, Xing-Qiu Chen, Cesare Franchini
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  ABSTRACT: By means of hybrid density functional theory we investigate the evolution of the structural, electronic, and magnetic properties of the colossal magnetoresistance (CMR) parent compound LaMnO3 under pressure. We predict a transition from a low-pressure antiferromagnetic (AFM) insulator to a high-pressure ferromagnetic (FM) transport half metal (tHM), characterized by a large spin polarization (≈80–90%). The FM-tHM transition is associated with a progressive quenching of the cooperative Jahn-Teller (JT) distortions which transform the Pnma orthorhombic phase into a perfect cubic one (through a mixed phase in which JT-distorted and regular MnO6 octahedra coexist), and with a high-spin (S=2, mMn=3.7μB) to low-spin (S=1, mMn=1.7μB) magnetic moment collapse. These results interpret the progression of the experimentally observed non-Mott metalization process and open up the possibility of realizing CMR behaviors in a stoichiometric manganite.
  Physical Review B 02/2012; 85:915135. · 3.69 Impact Factor
• Source

  Available from: Thomas Archer

  Article: Exceptionally strong magnetism in the 4d perovskites RTcO3 (R=Ca, Sr, Ba)

  C. Franchini, T. Archer, Jiangang He, Xing-Qiu Chen, A. Filippetti, S. Sanvito
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  ABSTRACT: The evolution of the magnetic ordering temperature of the 4d3 perovskites RTcO3 (R=Ca, Sr, Ba) and its relation with its electronic and structural properties has been studied by means of hybrid density functional theory and Monte Carlo simulations. When compared to the most widely studied 3d perovskites the large spatial extent of the 4d shells and their relatively strong hybridization with oxygen weaken the tendency to form Jahn-Teller like orbital ordering. This strengthens the superexchange interaction. The resulting insulating G-type antiferromagnetic ground state is characterized by large superexchange coupling constants (26–35 meV) and Neél temperatures (750–1200 K). These monotonically increase as a function of the R ionic radius due to the progressive enhancement of the volume and the associated decrease of the cooperative rotation of the TcO6 octahedra.
  Physical Review B 06/2011; 83:220402. · 3.69 Impact Factor
• Article: Exceptionally strong magnetism in the 4d perovskites RTcO_ {3}(R= Ca, Sr, Ba)

  C. Franchini, T. Archer, Jiangang He, Xing-Qiu Chen, A. Filippetti, S. Sanvito
  [show abstract] [hide abstract]
  ABSTRACT: The evolution of the magnetic ordering temperature of the 4d3 perovskites RTcO3 (R=Ca, Sr, Ba) and its relation with its electronic and structural properties has been studied by means of hybrid density functional theory and Monte Carlo simulations. When compared to the most widely studied 3d perovskites the large spatial extent of the 4d shells and their relatively strong hybridization with oxygen weaken the tendency to form Jahn-Teller like orbital ordering. This strengthens the superexchange interaction. The resulting insulating G-type antiferromagnetic ground state is characterized by large superexchange coupling constants (26–35 meV) and Neél temperatures (750–1200 K). These monotonically increase as a function of the R ionic radius due to the progressive enhancement of the volume and the associated decrease of the cooperative rotation of the TcO6 octahedra.
  Phys. Rev. B. 83(22).