Magnetic-field-induced formation of exciton magnetic polarons in ZnSe/Zn1-xMnxSe quantum-well structures.
Magnetic-field-induced formation of exciton magnetic polarons in ZnSe/Zn1-xMnxSe quantum-well structures.
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ZnSe/Zn1-xMnxSe 量子阱结构中磁场诱导形成激子磁极化子。
DOI：
10.1103/physrevb.53.16444
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Puls
中科院分区：
文献类型：
--
作者：
Rossin;Henneberger;Puls
利用连续波和时间分辨光致发光光谱研究了外加磁场作用下具有半像磁势垒的ZnSe/${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se量子阱。结果表明，主要的能量驰豫机制从零场下轻空穴激子的无序局域化转变为中场下重空穴激子界面磁极化子的形成，并再次证明了重空穴激子在大磁场中的无序局域化。重空穴激子的磁场感生I型-Char21型-II型跃迁促进了界面磁极化子的形成。尽管发生了跃迁，激子寿命和光学振子强度都没有显著改变。我们通过两粒子薛定谔方程的数值解证实，这是电子-空穴库仑相互作用的结果。极化子的形成时间最初为110ps，但随着磁场的增加而减小，直到70ps(B=5T)。对极化子形成动力学的理论研究表明，激子波函数的相关变化越小，自旋系统在外场作用下越接近饱和。结果表明，极化子的形成时间接近特征自旋响应时间。我们的测量揭示了在极化子过程\char22{}之前的快速初级局部化，但也是磁性起源的\char22{}，我们认为这是开始极化子形成所必需的。版权所有：1996美国物理学会。
cw and time-resolved photoluminescence spectroscopy is used to study ZnSe/${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se quantum wells with semimagnetic barriers in an external magnetic field. The data demonstrate a change of the dominant energy relaxation mechanism from disorder localization of light-hole excitons at zero-field to heavy-hole exciton interface magnetic polaron formation at intermediate fields and, again, disorder localization of heavy-hole excitons at large magnetic fields. The formation of the interface magnetic polaron is promoted by a magnetic-field-induced type-I\char21{}type-II transition for heavy-hole excitons. Despite the transition, neither the exciton lifetime nor its optical oscillator strength is dramatically altered. This is, as we confirm by numerical solution of the two-particle Schr\"odinger equation, a result of the electron-hole Coulomb interaction. The polaron formation time is initially 110 ps, but decreases with growing magnetic field down to 70 ps (B=5 T). A theoretical investigation of the polaron formation dynamics shows that the associated change of the exciton wave function is smaller, the closer the ${\mathrm{Mn}}^{2+}$ spin system is driven into saturation by the external field. As a consequence, the polaron formation time approaches the characteristic ${\mathrm{Mn}}^{2+}$ spin response time. Our measurement uncovers a fast primary localization prior to the polaron process\char22{}but also of magnetic origin\char22{}that we believe to be necessary to start the polaron formation. \textcopyright{} 1996 The American Physical Society.