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Colloquium

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Colloquium

The bellow is colloquium schedule in Physics department. Every Wednesday 4:00 PM, colloquium is held in seminar room (Science Building III -201) Also, Free tea time will be held 30 minutes before colloquium stars. Please visit and enjoy the colloquium and tea time.

 

Colloquium 장소 및 시간: 세미나실(공학3동 201호) 오후 4시
연락처 : 물리학과 김지훈교수 (279-2077), jeehoon@postech.ac.kr

          물리학과 사무실 김수경 (279-5971) skyung@postech.ac.kr

Investigation of Unconventional Magnetism and Superconductivity by Magnetic Force Microscopy

speaker : Prof. Jee-Hoon Kim[POSTECH]

location :

date : 2014-10-1

Recently, skyrmions have drawn much attention for physics and applied science since they provide a venue for domain manipulation with an ultra low current density. Skyrmions, originally, were found at the non-centrosymmetric crystals, such as MnSi and FeGe, originating from competition between ferromagnetic exchange and Dzyaloshinskii-Moriya interactions. However, a couple of recent results show skyrmion behavior in highly anisotropic magnetic materials with inversion symmetry, which opens a wide span of practical applications.

In the first part of the talk I will show skyrmion-like domains in centrosymmetric crystals, probed by magnetic force microscopy (MFM). In particular the evolution of tree-like domains into skyrmion-like bubbles is discussed with a variety of fields and temperature in the bilayer LSMO single crystals.

In the second part of the talk I would like to discuss how MFM can be applied to investigate superconductivity.

Recently, we developed a novel technique to measure the absolute value of the magnetic penetration depth in superconductors by MFM. This technique has been applied to unconventional superconductors, such as borocarbides, pnictides, and YBCO films irradiated by heavy ions to investigate intrinsic superconducting properties as well as vortex dynamics. We will present instrumentation of our new 4He MFM and 3He MFM and their application to superconductors via magnetic penetration depth. Specifically, I will present about investigation of the pairing symmetry by MFM.