Dmitry A. Yarotski

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Black TiO2 nanoparticles with a crystalline core and amorphous-shell structure exhibit superior optoelectronic properties in comparison with pristine TiO2. The fundamental mechanisms underlying these enhancements, however, remain unclear, largely due to the inherent complexities and limitations of powder materials. Here, we fabricate TiO2 homojunction films(More)
Ultrafast optical spectroscopy was utilized to investigate charge transfer dynamics across organic semiconductor tetracene/C60 interfaces in the presence of a LiF barrier layer. Photoinduced absorption spectra in the 1.6−2.3 eV range reveal a strong effect of the intermediate LiF barrier layer on dynamics of the charge transfer excitons (CTE) creation and(More)
Quasi-periodic excitation of the tunneling junction in a scanning tunneling microscope, by a mode-locked ultrafast laser, superimposes a regular sequence of 15 fs pulses on the DC tunneling current. In the frequency domain, this is a frequency comb with harmonics at integer multiples of the laser pulse repetition frequency. With a gold sample the 200th(More)
We present an experimental observation of the dynamics of an initially chirped optical soliton at 1.55microm that is propagating through a single-mode optical fiber, using frequency-resolved optical gating (FROG). FROG permits observation of both the amplitude and the phase profiles of ultrashort pulses, providing complete information on the pulse(More)
Strong coupling between discrete phonon and continuous electron-hole pair excitations can induce a pronounced asymmetry in the phonon line shape, known as the Fano resonance. This effect has been observed in various systems. Here we reveal explicit evidence for strong coupling between an infrared-active phonon and electronic transitions near the Weyl points(More)
Weiwei Li,1,2 Qian He,3 Le Wang,4 Huizhong Zeng,5 John Bowlan,6 Langsheng Ling,7 Dmitry A. Yarotski,6 Wenrui Zhang,8 Run Zhao,1 Jiahong Dai,9 Junxing Gu,4 Shipeng Shen,4 Haizhong Guo,4 Li Pi,7 Haiyan Wang,8 Yongqiang Wang,10 Ivan A. Velasco-Davalos,11 Yangjiang Wu,12 Zhijun Hu,12 Bin Chen,13 Run-Wei Li,13 Young Sun,4 Kuijuan Jin,4 Yuheng Zhang,7 Hou-Tong(More)
Strain is a novel approach to manipulating functionalities in correlated complex oxides. However, significant epitaxial strain can only be achieved in ultrathin layers. We show that, under direct lattice matching framework, large and uniform vertical strain up to 2% can be achieved to significantly modify the magnetic anisotropy, magnetism, and(More)
The mechanisms producing strong coupling between electric and magnetic order in multiferroics are not always well understood, since their microscopic origins can be quite different. Hence, gaining a deeper understanding of magnetoelectric coupling in these materials is the key to their rational design. Here, we use ultrafast optical spectroscopy to show(More)
A variety of emergent phenomena have been enabled by interface engineering in complex oxides. The existence of an intrinsic interfacial layer has often been found at oxide heterointerfaces. However, the role of such an interlayerin controlling functionalities is not fully explored. Here, we report the control of the exchange bias (EB) in single-phase(More)
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