The authors demonstrate readout of electrically detected magnetic resonance at radio frequencies by means of an LCR tank circuit. Applied to a silicon field-effect transistor at milli-kelvin temperatures, this method shows a 25-fold increased signal-to-noise ratio of the conduction band electron spin resonance and a higher operational bandwidth of > 300 kHz compared to the kHz bandwidth of conventional readout techniques. This increase in temporal resolution provides a method for future direct observations of spin dynamics in the electrical device characteristics.
SiC based metal-oxide-semiconductor field-effect transistors (MOSFETs) have gained a significant importance in power electronics applications. However, electrically active defects at the SiC/SiO$_2$ interface degrade the ideal behavior of the devices. The relevant microscopic defects can be identified by electron paramagnetic resonance (EPR) or electrically detected magnetic resonance (EDMR). This helps to decide which changes to the fabrication process will likely lead to further increases of device performance and reliability. EDMR measurements have shown very similar dominant hyperfine (HF)…
Spin-Dependent Recombination between Phosphorus Donors in Silicon and Si/SiO2 Interface States Investigated with Pulsed Electrically Detected Electron Double Resonance
Dielectric interfaces critical for metal-oxide-semiconductor (MOS) electronic devices, such as the Si/SiO$_2$ MOS field effect transistor (MOSFET), possess trap states that can be visualized with electrically-detected spin resonance techniques, however the interpretation of such measurements has been hampered by the lack of a general theory of the phenomena. This article presents such a theory for two electrical spin-resonance techniques, electrically detected magnetic resonance (EDMR) and the recently observed near-zero field magnetoresistance (NZFMR), by generalizing Shockley Read Hall trap-…
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…
Theory of Electrically Detected Magnetic Resonance of Silicon Vacancy-Related Spin Pairs in Silicon Carbide
University of Iowa（爱荷华大学）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Donostia International Physics Center（圣塞巴斯蒂安国际物理中心）；Coastal Carolina University（海岸卡罗来纳大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；Eindhoven University of Technology（埃因霍温理工大学）
Electrically detected magnetic resonance of $^{75}$As magnetic clock transitions in silicon
University of Melbourne（墨尔本大学）；University of Manchester（曼彻斯特大学）；University College London（伦敦大学学院）；RMIT University（皇家墨尔本理工大学）；Australian Research Council Centre for Quantum Computation and Communication Technology（澳大利亚研究委员会量子计算与通信技术中心）；CSIRO（联邦科学与工业研究组织）
We describe a simple experimental method to detect electron paramagnetic resonance (EPR) in polycrystalline 2,2-diphenyl-1-picrylhydrazyl (DPPH) sample, the standard g-marker for EPR spectroscopy, without using a cavity resonator or a prefabricated waveguide. It is shown that microwave(MW) current injected into a layer of silver paint coated on an insulating DPPH sample is able to excite the paramagnetic resonance in DPPH. As the applied dc magnetic field H is swept, the high-frequency resistance of the Ag-paint layer, measured at room temperature with a single port impedance analyzer in the M…
Electrical detection of the 180 deg spin reversal, which is the basis of the operation of ferromagnetic memories, is among the outstanding challenges in the research of antiferromagnetic spintronics. Analogous effects to the ferromagnetic giant or tunneling magnetoresistance have not yet been realized in antiferromagnetic multilayers. Anomalous Hall effect (AHE), which has been recently employed for spin reversal detection in non-collinear antiferromagnets, is limited to materials that crystalize in ferromagnetic symmetry groups. Here we demonstrate electrical detection of the 180 deg Néel vec…
Triplet excited states in organic semiconductor materials and devices are notoriously difficult to detect and study with established spectroscopic methods. Yet, they are a crucial intermediate step in next-generation organic light emitting diodes (OLED) that employ thermally activated delayed fluorescence (TADF) to upconvert non-emissive triplets to emissive singlet states. In organic photovoltaic (OPV) devices, however, triplets are an efficiency-limiting exciton loss channel and are also involved in device degradation. Here, we introduce an innovative spin-sensitive method to study triplet s…
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…
Using electrically detected magnetic resonance spectroscopy, we demonstrate that doping the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) with ethylene glycol allows for the control of effective local charge carrier hyperfine fields through motional narrowing. These results suggest that doping of organic semiconductors could enable the tuning of macroscopic material properties dependent on hyperfine fields such as magnetoresistance, the magneto-optical responses and spin-diffusion.
Electrically injected and detected nonlocal magnon transport has emerged as a versatile method for transporting spin as well as probing the spin excitations in a magnetic insulator. We examine the role of drift currents in this phenomenon as a method for controlling the magnon propagation length. Formulating a phenomenological description, we identify the essential requirements for existence of magnon drift. Guided by this insight, we examine magnetic field gradient, asymmetric contribution to dispersion, and temperature gradient as three representative mechanisms underlying a finite magnon dr…
Recent research works have shown that the magnetic order in some antiferromagnetic materials can be manipulated and detected electrically, due to two physical mechanisms: Neel-order spin-orbit torques and anisotropic magnetoresistance. While these observations open up opportunities to use antiferromagnets for magnetic memory devices, different physical characterization methods are required for a better understanding of those mechanisms. Here we report a magnetic field induced rotation of the antiferromagnetic Neel vector in epitaxial tetragonal CuMnAs thin films. Using soft x-ray magnetic line…
Separating the influence of hyperfine from spin-orbit interactions in spin-dependent carrier recombination and dissociation processes necessitates magnetic resonance spectroscopy over a wide range of frequencies. We have designed compact and versatile coplanar waveguide resonators for continuous-wave electrically detected magnetic resonance, and tested these on organic light-emitting diodes. By exploiting both the fundamental and higher-harmonic modes of the resonators we cover almost five octaves in resonance frequency within a single setup. The measurements with a common pi-conjugated polyme…
We measure electrically detected magnetic resonance (EDMR) on organic light-emitting diodes (OLEDs) made of the polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) at room temperature and high magnetic fields, where spectral broadening of the resonance due to spin-orbit coupling (SOC) exceeds that due to the local hyperfine fields. Density-functional-theory calculations on an open-shell model of the material reveal g-tensors of charge-carrier spins in the lowest unoccupied (electron) and highest occupied (hole) molecular orbitals. These tensors are used for simulations …
The magneto-electronic field effects in organic semiconductors at high magnetic fields are described by field-dependent mixing between singlet and triplet states of weakly bound charge carrier pairs due to small differences in their Landé g-factors that arise from the weak spin-orbit coupling in the material. In this work, we corroborate theoretical models for the high-field magnetoresistance of organic semiconductors, in particular of diodes made of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) at low temperatures, by conducting magnetoresistance …
Nonreciprocal Magnon Hanle Effect in Antiferromagnetic $α$-Fe$_2$O$_3$
Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften（瓦尔特·迈斯纳研究所，巴伐利亚科学院）；TUM School of Natural Sciences, Technische Universität München（慕尼黑工业大学自然科学学院）；Condensed Matter Physics Center (IFIMAC) and Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid（马德里自治大学凝聚态物理中心（IFIMAC）和凝聚态物质理论物理系）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）
Several spin-orbit effects allow performing spin to charge inter-conversion: the spin Hall effects, the Rashba effect, or the spin-momentum locking in topological insulators. Here we focus on how the detection of this inter-conversion can be made electrically, using three different cross-shaped nanostructures. We apply these measurement configurations to the case of the spin Hall effect in Pt, using CoFe electrodes to detect and inject spins. Both the direct and inverse spin Hall effect can be detected, with a spin Hall signal up to two order of magnitude higher than that of nonlocal measureme…
We experimentally investigate magnon-polaritons, arising in ferrimagnetic resonance experiments in a microwave cavity with a tuneable quality factor. To his end, we simultaneously measure the electrically detected spin pumping signal and microwave reflection (the ferrimagnetic resonance signal) of a yttrium iron garnet (YIG) / platinum (Pt) bilayer in the microwave cavity. The coupling strength of the fundamental magnetic resonance mode and the cavity is determined from the microwave reflection data. All features of the magnetic resonance spectra predicted by first principle calculations and a…
The spin Seebeck effect (SSE) refers to the generation of a spin current as a result of a temperature gradient in a magnetic material, which can be detected electrically via the inverse spin Hall effect in a metallic contact. Since the discovery of SSE in 2008, intensive studies on SSE have been conducted to elucidate its origin. SSEs appear in a wide range of magnetic materials including ferro-, ferri-, and antiferro-magnets and also paramagnets with classical or quantum spin fluctuation. SSE voltage reflects fundamental properties of a magnet, such as elementary excitation, static magnetic o…
Numerical study of spin-dependent transition rates within pairs of dipolar and strongly exchange coupled spins with (s=1/2) during magnetic resonant excitation
