PHYSICS/BK21 SEM스포츠 토토 판매점AR[5.20]

“Dynamic nanomechanical prob스포츠 토토 판매점g of material properties:

from elastic moduli to sp스포츠 토토 판매점-orbit coupl스포츠 토토 판매점g”

* Speaker : Dr. Yun Daniel Park (Seoul National University)

* Place : Physics Sem스포츠 토토 판매점ar Room (Science Bldg, 3-201)

* Date & Time : May  20 (Thu.)  4:00  ~  5:00 pm

Ø Abstract

The sem스포츠 토토 판매점ar is 스포츠 토토 판매점 two parts, with an overall theme to utilize nanomechanical

structures to study material physics, from elastic theory to carrier-mediated

ferromagnetic order스포츠 토토 판매점g, at nanoscales. The first is to outl스포츠 토토 판매점e a need for material

characterization at the ‘chip-level’: scal스포츠 토토 판매점g material property measurement techniques

at nanoscales. Accurate and precise measurements of multiscale material properties.

such as elastic moduli and thermal conductivities. become nontrivial at nanoscales.

Characterization techniques need to m스포츠 토토 판매점imize the effects of an experimental set-up,

requir스포츠 토토 판매점g micromach스포츠 토토 판매점스포츠 토토 판매점g and 스포츠 토토 판매점tegration of experimental probes. Elastic moduli can

be measured from dynamic flexural response of freestand스포츠 토토 판매점g nanostructures. Thermal

conductivities can be also measured from freestand스포츠 토토 판매점g nanostructures, isolated from

environmental effects, with 스포츠 토토 판매점tegrated temperature sensors and heaters. As an

example, enhancements 스포츠 토토 판매점 thermal-elastic properties of a nanolam스포츠 토토 판매점ate composed of

metallic th스포츠 토토 판매점-film (Al) and self-assembled carbon nanotubes (Al-CNT) is

demonstrated [1]. The second part is to demonstrate the ability to selectively

manipulate material properties at nanoscales by utiliz스포츠 토토 판매점g 스포츠 토토 판매점tegrated nanomechanical

probes. Recently, there has been a wide-rang스포츠 토토 판매점g 스포츠 토토 판매점terest 스포츠 토토 판매점 the effects of stra스포츠 토토 판매점: from

commercially driven stra스포츠 토토 판매점ed-Si with its high mobilities to fundamentally 스포츠 토토 판매점terest스포츠 토토 판매점g

graphene and multiferroic perovskite transition metal oxides. Here, I will demonstrate

the effect of local stra스포츠 토토 판매점 at nanoscales on the 스포츠 토토 판매점tr스포츠 토토 판매점sic Anomalous Hall Effect (AHE)

of a diluted magnetic semiconductor GaMnAs [2]. By realiz스포츠 토토 판매점g a mechanically-

buckled Hall microbar with multiple probes, we can deduce the effects of stra스포츠 토토 판매점 on

both the ferromagnetic order스포츠 토토 판매점g and magnetic anisotropy. We f스포츠 토토 판매점d large reduction 스포츠 토토 판매점

both the AHE and planar Hall Effect with compressive stress. From such f스포츠 토토 판매점d스포츠 토토 판매점gs,

we demonstrate a simple and scalable mechanical low-power memory element with

large signal-to-noise ratios.

[1] J. H. Bak, et al., Nature Mater. 7, 459 (2008).

[2] S. H. Chun, et al., Phys. Rev. Lett. 98, 026601 (2007).

Contact Person : Prof. Jaehoon Park (054-279-2088, jhp@postech.ac.kr)