Karolina Ewa Połczyńska

• Master of Science
• University of Warsaw

Optically detected magnetic resonance (ODMR) is a useful technique for studying interactions between local spins (magnetic ions) and the carrier gas. We present an ODMR study of a single ( Cd , Mn ) Te / ( Cd , Mg ) Te quantum wells (QWs) with the hole gas. We observe different characteristics of the ODMR signals obtained simultaneously using the o...

In this work, we study the impact of carrier localization on three quantities sensitive to carrier gas density at the micrometer scale: charged exciton (X+) oscillator strength, local free carrier conductivity, and the Knight shift. The last two are observed in a micrometer-scale, spatially resolved optically detected magnetic resonance experiment...

We present the basic properties of a new physical system: an individual V2+ ion embedded into an individual quantum dot. The system is realized utilizing molecular beam epitaxy and it is observed using a low-temperature polarization-resolved magneto-photoluminescence. The nature of the system is confirmed by observation of the excitonic lines split...

Optically detected magnetic resonance (ODMR) is a useful technique for studying interactions between local spins (magnetic ions) and carrier gas. We present the ODMR study of single (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) with the hole gas. We observe different characteristics of the ODMR signals obtained simultaneously using the optical signals of...

Using four-wave mixing microscopy, we measure the coherent response and ultrafast dynamics of excitons and trions in MoSe2 monolayers grown by molecular beam epitaxy on thin films of hexagonal boron nitride. We assess inhomogeneous and homogeneous broadenings in the transition spectral lineshape. The impact of phonons on the homogeneous dephasing i...

Using four-wave mixing microscopy, we measure the coherent response and ultrafast dynamics of excitons and trions in MoSe$_2$ monolayers grown by molecular beam epitaxy on thin films of hexagonal boron nitride. We assess inhomogeneous and homogeneous broadenings in the transition spectral lineshape. The impact of phonons on the homogeneous dephasin...

Time-resolved optically detected magnetic resonance (ODMR) is a valuable technique to study the local deformation of the crystal lattice around magnetic ion as well as the ion spin-relaxation time. Here we utilize selective Mn doping to additionally enhance the inherent locality of the ODMR technique. We present the time-resolved ODMR studies of si...

Time-resolved optically detected magnetic resonance (ODMR) is a valuable technique to study the local deformation of the crystal lattice around magnetic ion and its relaxation time. Here we utilize selective Mn-doping to additionally enhance the inherent locality of the ODMR technique. We present the time-resolved ODMR studies of single {(Cd,Mg)Te/...

In this paper, we apply the angle-resolved optically detected magnetic resonance (ODMR) technique to study a series of strained (Cd, Mn)Te/(Cd, Mg)Te quantum wells (QWs) produced by molecular beam epitaxy. By analyzing characteristic features of ODMR angular scans, we determine the strain-induced axial-symmetry spin Hamiltonian parameter D with neV...

Using ultrafast resonant pump-probe spectroscopy in an unconventional experimental setup we investigate the spectral shape and dynamics of absorption features related to the A exciton in an hexagonal boron nitride (hBN)/MoSe2/hBN van der Waals heterostructure. While in a pure two-level system a pump-probe experiment measures the occupation or the p...

In this paper, we apply the angle-resolved Optically Detected Magnetic Resonance (ODMR) technique to study series of strained (Cd, Mn)Te/(Cd, Mg)Te quantum wells (QWs) produced by molecular beam epitaxy. By analyzing characteristic features of ODMR angular scans, we determine strain-induced axial-symmetry spin Hamiltonian parameter D with neV preci...

Using ultrafast resonant pump-probe spectroscopy we investigate A exciton dynamics in an hBN/MoSe$_2$/hBN van der Waals heterostructure. While in a pure two-level system a pump-probe experiment measures the occupation or the polarization dynamics, depending on the time ordering of the pulse pair, in our case both quantities get mixed by the interac...

We report on the magneto-photoluminescence of (Cd,Mn)Te/(Cd,Mg)Te quantum wells excited by photons with varied energy. We observe that laser illumination modifies the carrier density and Coulomb disorder in the quantum wells. Three different regimes are analyzed, corresponding to low hole density with low disorder, low hole density with significant...

Wurtzite CdTe and (Cd,Mn)Te nanowires embedded in (Cd,Mg)Te shells are grown by employing vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. A combined study involving cathodoluminescence, transmission electron microscopy and micro-photoluminescence is used to correlate optical and structural properties in these structures....

Monolayer transition metal dichalcogenides (TMDs) manifest exceptional optical properties related to narrow excitonic resonances. However, these properties have been so far explored only for structures produced by techniques inducing considerable large-scale inhomogeneity. In contrast, techniques which are essentially free from this disadvantage, s...