Complex Materials for Multifunctionaities
Complex transition metal oxides those with several different oxidation states in transition metals showing strong correlation among spin, charge, and lattice – have become popular and important subjects of study in condensed matter physics and materials physics. At Pusan National University (PNU), we will build a cutting-edge research program focused on not only epitaxial synthesis of the complex transition metal oxide thin films and heterostructures, but also on various characterization techniques for explore their structural, electronic, magnetic, and electrochemical properties. Thereby, we will explore fundamentals as well as applications. The successful synthesis of the high quality and chemically well-defined thin films and heterostructures is an intricate process. But can be extremely useful for understanding origins of the exotic phenomena and finding suitable applications. Our research target is to uncover the fundamental magnetic and electronic properties as well as electrochemical properties of the complex oxides.
In addition to complex oxide thin films, we have worked on expanding our capability in non-oxide materials. Especially, we have put our efforts on thin film growth and characterizations of epitaxial metal-alloy and metal-nitride for next-generation rare-earth free permanent magnets(PMs) . Rare earth-based PMs have dominated magnet markets, however temperature stability and limited availability of rare earth elements have led us to work on developing new permanent magnets. we have focused on enhancing structural (or magnetocrystalline) anisotropy in order for coercivity engineering. It is very elusive task, but it can be beneficial for us in everyday life applications.
These broad interests and experiences on the matters allow us to easily engage in rapidly developing scientific areas in almost all the condensed matter physics and materials physics. Collaboration within PNU, as well as with external labs such as Oak Ridge National Laboratory, Pohang Accelerator Laboratory, Korea Atomic Energy Research Institute, and etc, are established to utilize state-of-art advanced characterization techniques to fully understand role of multiple valence states, structure-property relationship, and interface coupling in heterostructures synthesized in our lab. Thereby further improving the scientific impact and productivity of my group and existing programs at PNU.
Lastly, as a part of expand our knowledge, we are actively taking part in Frontiers in Physics seminar series as well as Department colloquium.
Materials list and Research directions (not complete)
- Epitaxial Oxygen Sponges: SrFe1-xCoxOy
- Binary oxides and multilayers: MoOx, NbOx
- Thin film supercapacitors (collaboration): La0.5Sr0.5CoO3
- Thin film thermoelectrics (collaboration)
- Others: Sr3Al2O6, (La,Sr)(Cr,Mn)O3, ionic conductors etc.
Magnetism in Complex Oxides
- Double Perovskites: PrBaCo2O5.5
- Hole-doped manganites: Nd1-xSrxMnO3, Pr1-xCaxMnO3 (TEM collaboration), La1-xSrxMnO3
- Polarized neutron reflectometry (collaboration)
- Magnetic neutron diffraction (collaboration) BiMnO3
Hard/soft magnets and multiferroics
- Intermetaillic and intermetallic nitride thin films: Co, Fe, Fe-Al, FeNi, and Sm-Fe, Gd-Fe, Ce-Fe, etc.
- Ferrites: SrFe12O19 and Ga2-xFexO3
- Ion implantation: Mo2N, CeFe12N
Physics of oxide single crystals
- 2D materials: Fe1+xTe, Se doped FeTe
- Layered oxides: MoO3 (not active)