We show that in pulsed electrically detected magnetic resonance (pEDMR) signal modulation in combination with a lock-in detection scheme can reduce the low-frequency noise level by one order of magnitude and in addition removes the microwave-induced non-resonant background. This is exemplarily demonstrated for spin-echo measurements in phosphorus-doped Silicon. The modulation of the signal is achieved by cycling the phase of the projection pulse used in pEDMR for the read-out of the spin state.
We present pulsed electrically detected magnetic resonance (EDMR) measurements at low magnetic fields using posphorus-doped silicon with natural isotope composition as a model system. Our measurements show that pulsed EDMR experiments, well established at X-band frequencies (10 GHz), such as coherent spin rotations, Hahn echoes, and measurements of parallel and antiparallel spin pair life times are also feasible at frequencies in the MHz regime. We find that the Rabi frequency of the coupled 31P electron-nuclear spin system scales with the magnetic field as predicted by the spin Hamiltonian, w…
Several microscopic pathways have been proposed to explain the large magnetic effects observed in organic semiconductors, but identifying and characterising which microscopic process actually influences the overall magnetic field response is challenging. Pulsed electrically-detected magnetic resonance provides an ideal platform for this task as it intrinsically monitors the charge carriers of interest and provides dynamical information which is inaccessible through conventional magnetoconductance measurements. Here we develop a general time domain theory to describe the spin-dependent reaction…
We investigate the spin species relevant for the spin-dependent recombination used for the electrical readout of coherent spin manipulation in phosphorus-doped silicon. Via a multi-frequency pump-probe experiment in pulsed electrically detected magnetic resonance, we demonstrate that the dominant spin-dependent recombination transition occurs between phosphorus donors and Si/SiO2 interface states. Combining pulses at different microwave frequencies allows us to selectively address the two spin subsystems participating in the recombination process and to coherently manipulate and detect the rel…
Here we describe a new high frequency/high field continuous wave and pulsed electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating at 263 GHz and resonance fields between 0 and 12 T. Spin dependent transport in illuminated hydrogenated amorphous silicon p-i-n solar cells at 5 K and 90 K was studied by in operando 263 GHz CW and pEDMR alongside with complementary X-band CW EDMR. Benefiting from the superior resolution at 263 GHz, we were able to better resolve EDMR signals originating from spin dependent hopping and recombination processes. 5 K EDMR spectra were found to …
The investigation of paramagnetic species (such as point defects, dopants, and impurities) in solid-state electronic devices is significant because of their effect on device performance. Conventionally, these species are detected and imaged using the electron spin resonance (ESR) technique. In many instances, ESR is not sensitive enough to deal with miniature devices having small numbers of paramagnetic species and high spatial heterogeneity. This limitation can in principle be overcome by employing a more sensitive method called electrically-detected magnetic resonance, which is based on meas…
We demonstrate the electrical detection of pulsed X-band Electron Nuclear Double Resonance (ENDOR) in phosphorus-doped silicon at 5\,K. A pulse sequence analogous to Davies ENDOR in conventional electron spin resonance is used to measure the nuclear spin transition frequencies of the $^{31}$P nuclear spins, where the $^{31}$P electron spins are detected electrically via spin-dependent transitions through Si/SiO$_2$ interface states, thus not relying on a polarization of the electron spin system. In addition, the electrical detection of coherent nuclear spin oscillations is shown, demonstrating…
Detection is most often the main impediment to reduce the number of spins in paramagnetic resonance experiments. Here we propose a new route to carry out electrically-detected spin resonance of an individual spin, placed at the edge of a quantum spin Hall insulator (QSHI). The edges of a QSHI host a one dimensional electron gas with perfect spin-momentum locking. Therefore, the spin relaxation induced by emission of an electron-hole pair at the edge state of the QSHI can generate current. Here we demonstrate that driving the system with an $AC$ signal, a nonequilibrium occupation can be induce…
The electron spins of semiconductor defects can have complex interactions with their host, particularly in polar materials like SiC where electrical and mechanical variables are intertwined. By combining pulsed spin resonance with ab-initio simulations, we show that spin-spin interactions within SiC neutral divacancies give rise to spin states with an enhanced Stark effect, sub-10**-6 strain sensitivity, and highly spin-dependent photoluminescence with intensity contrasts of 15-36%. These results establish SiC color centers as compelling systems for sensing nanoscale fields.
Spin-dependent relaxation and recombination processes in $γ$-irradiated $n$-type Czochralski-grown silicon are studied using continuous wave (cw) and pulsed electrically detected magnetic resonance (EDMR). Two processes involving the SL1 center, the neutral excited triplet state of the oxygen-vacancy complex, are observed which can be separated by their different dynamics. One of the processes is the relaxation of the excited SL1 state to the ground state of the oxygen-vacancy complex, the other a charge transfer between $^{31}$P donors and SL1 centers forming close pairs, as indicated by elec…
Electron valleys in transition-metal dichalcogenide monolayers drive novel physics and allow designing multifunctional architectures for applications. We propose to manipulate the electron valleys in these systems for spin/valley filter and valve devices through band engineering. Instead of the magnetic proximity effect that has been extensively used in previous studies, in our strategy, the electron valleys are directly coupled to the spin-polarized states of the two-dimensional ferromagnets. We find that this coupling results in a valley-selective gap opening due to the spin-momentum locking…
We present experiments to systematically study the time constants of spin-dependent recombination processes in semiconductors using pulsed electrically detected magnetic resonance (EDMR). The combination of time-programmed optical excitation and pulsed spin manipulation allows us to directly measure the recombination time constants of electrons via localized spin pairs and the time constant of spin pair formation as a function of the optical excitation intensity. Using electron nuclear double resonance, we show that the time constant of spin pair formation is determined by an electron capture …
We have studied the role of spin-dependent processes on conductivity in polyfluorene (PFO) thin films by conducting continuous wave (c.w.) electrically detected magnetic resonance (EDMR) spectroscopy at temperatures between 10 K and 293 K using microwave frequencies between about 100 MHz and 20 GHz as well as pulsed EDMR at X-band. Variable frequency EDMR allows us to establish the role of spin-orbit coupling in spin-dependent processes, pulsed EDMR probes coherent spin motion effects. We used PFO for this study in order to allow for the investigation of the effects of microscopic morphologica…
We demonstrate that the bandwidth of pulsed electrically detected magnetic resonance can be increased to at least 80 MHz using a radio frequency-reflectometry detection scheme. Using this technique, we measure coherent spin oscillations in real time during a resonant microwave pulse. We find that the observed signal is in quantitative agreement with simulations based on rate equations modeling the recombination dynamics of the spin system under study. The increased bandwidth opens the way to electrically study faster spin-dependent recombination processes, e.g., in direct semiconductors which …
We have studied the nature and dynamics of spin-dependent charge carrier recombination in Tris(8-hydroxyquinolinato) aluminum (Alq$_3$) films in light emitting diodes at room temperature using continuous wave and pulsed electrically detected magnetic resonance (EDMR) spectroscopy. We found that the EDMR signal is dominated by an electron-hole recombination process, and another, weaker EDMR signal whose fundamental nature was investigated. From the pulsed EDMR measurements we obtained a carrier spin relaxation time, $T_2 = 45\pm 25$ ns which is much shorter than $T_2$ in conjugated polymers, bu…
This study focuses on the synthesis of FeRh nanoparticles via pulsed laser ablation in liquid and on controlling the oxidation of the synthesized nanoparticles. Formation of monomodal γ-FeRh nanoparticles was confirmed by transmission electron microscopy (TEM) and their composition confirmed by atom probe tomography (APT). On these particles, three major contributors to oxidation were analysed: 1) dissolved oxygen in the organic solvents, 2) the bound oxygen in the solvent and 3) oxygen in the atmosphere above the solvent. The decrease of oxidation for optimized ablation conditions was confirm…
Circularly polarized photons are known to generate a directional helicity-dependent photocurrent in three-dimensional topological insulators at room temperature. Surprisingly, the phenomenon is readily observed at photon energies that excite electrons to states far above the spin-momentum locked Dirac cone and the underlying mechanism for the helicity-dependent photocurrent is still not understood. We resolve the puzzle through a comprehensive study of the helicity-dependent photocurrent in (Bi,Sb)_2Te_3 thin films as a function of the incidence angle of the optical excitation, its wavelength,…
Pulsed electrically-detected magnetic resonance of phosphorous (31P) in bulk crystalline silicon at very high magnetic fields (B > 8.5 T) and low temperatures (T = 2.8 K) is presented. We find that the spin-dependent capture and reemission of highly polarized (>95%) conduction electrons by equally highly polarized 31P donor electrons introduces less decoherence than other mechanisms for spin-to-charge conversion. This allows the electrical detection of spin coherence times in excess of 100 microseconds: 50 times longer than the previous maximum for electrically-detected spin readout experiment…
We have performed continuous wave and pulsed electron spin resonance measurements of implanted bismuth donors in isotopically enriched silicon-28. Donors are electrically activated via thermal annealing with minimal diffusion. Damage from bismuth ion implantation is repaired during thermal annealing as evidenced by narrow spin resonance linewidths (B_pp=12uT and long spin coherence times T_2=0.7ms, at temperature T=8K). The results qualify ion implanted bismuth as a promising candidate for spin qubit integration in silicon.
The effect of dipolar and exchange interactions within pairs of paramagnetic electronic states on Pauli-blockade-controlled spin-dependent transport and recombination rates during magnetic resonant spin excitation is studied numerically using the superoperator Liouville-space formalism. The simulations reveal that spin-Rabi nutation induced by magnetic resonance can control transition rates which can be observed experimentally by pulsed electrically (pEDMR) and pulsed optically (pODMR) detected magnetic resonance spectroscopies. When the dipolar coupling exceeds the difference of the pair part…
We investigate the effect of a direct current on propagating spin waves in a CoFeB/Ta bilayer structure. Using the micro-Brillouin light scattering technique, we observe that the spin wave amplitude may be attenuated or amplified depending on the direction of the current and the applied magnetic field. Our work suggests an effective approach for electrically controlling the propagation of spin waves in a magnetic waveguide and may be useful in a number of applications such as phase locked nano-oscillators and hybrid information processing devices.
