Some interesting physics in transition metal oxides: charge ordering, orbital ordering and spin-charge separation C. D. Hu Department of physics National Taiwan University 1. Introduction to double-exchange interaction (DE) 2. Introduction to charge ordering 3. Introduction to orbital ordering and orbital dynamics 4. Interplay between double-exchange interaction, charge ordering, and orbital ordering
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C. D. Hu Department of physics National Taiwan University
Some interesting physics in transition metal oxides: charge ordering, orbital ordering and spin-charge separation. C. D. Hu Department of physics National Taiwan University. 1. Introduction to double-exchange interaction (DE) 2. Introduction to charge ordering - PowerPoint PPT Presentation
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Some interesting physics in transition metal oxides: charge ordering, orbital ordering and spin-charge separation
C. D. HuDepartment of physics
National Taiwan University
1. Introduction to double-exchange interaction (DE) 2. Introduction to charge ordering 3. Introduction to orbital ordering and orbital dynamics4. Interplay between double-exchange interaction, charge ordering, and orbital ordering
Double-exchange interaction
La1-xDxMnO3 D: divalent elements 3-d
Lan(1-x)Sr1+nxMnnO3n+1 n = # of layers. 2-d
Phase diagram
OOI
CMR: Temperature Dependence
The electrical resistance depends strongly on applied magnetic field. As the temperature is increased through the ferromagnetic Curie temperature Tc, the MR ration rises sharply.
Manganites Structure
LaMnO3 La+3 Mn+3 O-23
Mn+3 3d4 xy, yz, zx orbitals form t2g band, localized spin 3/2 x2-y2, 3z2-r2 form eg band, mobile spin 1/2 S=3/2+1/2 -------doping-----
1. The energy of 4p state is affected by the electrons at 3d state.2. The energies of 4p state of Mn3+ and Mn4+ are different.3. Intensity varies with the direction of polarization due to the Aj coupling.4. Incident photon: polarization. z-axis: b direction. orbitals: y2-z2 and x2-z2.