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  >>> Topics >>> Novel Functional Materials for Spintronics
 
Generation and manipulation of nonlocal entangled electrons
Physics of Intrinsic Josephson Junctions and Terahertz Emission
Quasiparticles in
Quasi-1D Quantum Spin Systems
Novel Functional Materials for Spintronics
Physics of Vortex Matter in Type II Superconductors


 

The key issue for realizing the spintronics technology is to manipulate at will both the spin and charge degrees of freedom of electrons. Half metals (HMs) are unique materials, which are metallic for electrons of a single spin channel, and are expected as the fundamental block in spintronics. All HMs confirmed so far show net magnetism. These so-called half metallic ferromagnets (HMFMs) are understood naturally from the asymmetric densities of states in the two spin channels. In principle it is possible to have the spins of the occupied states compensate completely. Dubbed as half metallic antiferromagnet (HMAFM), this material will not influence surrounding devices in applications by the stray field, which is inevitable for known HMFMs.

We have investigated theoretically a class of perovskite cuprates in order to search new HM. The parent material Sr8CaRe3Cu4O24 is a Mott insulator due to the strong correlations of electrons; it exhibits a ferrimagnetic ground state with Tc=440K accompanied by charge and orbital orders in Cu cations. Based on first-principles calculations within the DFT+U scheme, we found that doping one hole, which can be realized by replacing one of the eight divalent Sr atoms with one univalent Rb or K atom (known as A-site substitution), makes the system metallic in a single spin channel, and thus HM; the net magnetization of the parent ferrimagnetic compound is cancelled by the spin of the doped hole, and thus the system shows no macroscopic magnetization. This new compound is thus predicted to be a candidate of HMAFM. Very recently, we have been engaging in search for HMs in iron pnictides and obtained very intriguing results.


Figure: Isosurface of spin-magnetization density for the parent material Sr8CaRe3Cu4O24(left) and doped material (right). The pink/blue color is for plus/minus magnetization. The cutoff is 0.07��B/A3.

For more details, please refer to the attached pdf file

 

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