DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | Ahn, Jae-Wook | - |
dc.contributor.advisor | 안재욱 | - |
dc.contributor.author | Jang, Kyeong-Jin | - |
dc.contributor.author | 장경진 | - |
dc.date.accessioned | 2011-12-14T07:28:46Z | - |
dc.date.available | 2011-12-14T07:28:46Z | - |
dc.date.issued | 2010 | - |
dc.identifier.uri | http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=455322&flag=dissertation | - |
dc.identifier.uri | http://hdl.handle.net/10203/47652 | - |
dc.description | 학위논문(박사) - 한국과학기술원 : 물리학과, 2010.08, [ ⅸ, 95 p. ] | - |
dc.description.abstract | The pump-probe experiment on manganites, which are colossal magnetoresistance materials, $La_{1/4}Pr_{3/8}Ca_{3/8}MnO_3$ and multiferroic materials, $LuMnO_3$ and $YMnO_3$ are carried out. The hole-doped rare-earth manganite, e.g. $La_{1-x}Ca_xMnO_3$, shows colossal agnetoresistance and different temperature-dependent phases. For $0.2<x<0.5$, it displays ferromagnetic metallic behavior at low temperature. For $x>0.5$ it shows charge-ordering phase at low temperature. If substituting Pr for La in $La_{5/8}Ca_{3/8}MnO_3$, the ferromagnetic metallic and charge-ordering phases are coexist at low temperature. For this sample, $La_{1/4}Pr_{3/8}Ca_{3/8}MnO_3$, the coherent optical and acoustic phonons are observed using femtosecond pump-probe spectroscopy. emperature dependent measurements of the time-resolved optical reflectance revealed that the energy of the photoexcited electrons dissipated during relaxation to acoustic phonons, in the high-temperature paramagnetic phase, and to optical phonons, in the low-temperature charge-ordering phase. Analysis of the temperature-dependent behavior reveals that the modal amplitudes of the coherent phonons appear strongly correlated with the charge-ordering phase. Hexagonal multiferroics, $LuMnO_3$ and $YMnO_3$, are different types of rare-earth manganites. These materials have hexagonal structure in $ab$ plane and display phase transitions: a ferroelectric phase transition at high temperature $\sim$900 K, an antiferromagnetic phase transition at 90 K ($LuMnO_3$) or 80 K ($YMnO_3$). These hexagonal rare-earth manganites show multiferroic properties, which coupled electrical(ferroelectricity) and magnetic(antiferromagnetic) properties. In the $LuMnO_3$ thecoherent optical and acoustic phonons are generated above antiferromagnetic phase transition temperature ($T_{\rmN}$), while both couldn`t generated below $T_{\rm N}$. In the $YMnO_3$, the abrupt change of coherent acoustic phonon was measured. These temperature-dependent be... | eng |
dc.language | eng | - |
dc.publisher | 한국과학기술원 | - |
dc.subject | multiferroic | - |
dc.subject | LPCMO | - |
dc.subject | coherent phonon | - |
dc.subject | pump-probe | - |
dc.subject | 펌프-프로브 | - |
dc.subject | 자기저항효과물질 | - |
dc.subject | 다강체 | - |
dc.subject | 결맞음 포논 | - |
dc.title | (The) study of coherent optical and acoustic phonons in correlated electron materials | - |
dc.title.alternative | 거대자기저항효과 물질과 다강체 물질에서의 결맞음 포논에 대한 연구 | - |
dc.type | Thesis(Ph.D) | - |
dc.identifier.CNRN | 455322/325007 | - |
dc.description.department | 한국과학기술원 : 물리학과, | - |
dc.identifier.uid | 020037546 | - |
dc.contributor.localauthor | Jang, Kyeong-Jin | - |
dc.contributor.localauthor | 장경진 | - |
dc.title.subtitle | CMR, multiferroic | - |
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