Publications de Ferenc Simon | EPFL Graph Search

Terahertz emission from diamond nitrogen-vacancy centers

László Forró, Ferenc Simon, Sándor Kollarics, Bence Gábor Márkus

Coherent light sources emitting in the terahertz range are highly sought after for fundamental research and applications. Terahertz lasers rely on achieving population inversion. We demonstrate the generation of terahertz radiation using nitrogen-vacancy c ...

Amer Assoc Advancement Science2024

Ultralong Charge Carrier Recombination Time in Methylammonium Lead Halide Perovskites

László Forró, Andrzej Sienkiewicz, Márton Kollár, Ferenc Simon

Due to their exceptional photovoltaic properties, metal halide perovskites (MHPs) are extensively studied for their potential applications in solar cells. In recent years, the power conversion efficiencies of MHPs-based solar cells rapidly increased from t ...

2022

Non-exponential magnetic relaxation in magnetic nanoparticles for hyperthermia

Ferenc Simon, Bence Gábor Márkus

Magnetic nanoparticle based hyperthermia emerged as a potential tool for treating malignant tumours. The efficiency of the method relies heavily on the knowledge of magnetic properties of the samples; in particular, knowledge of the frequency dependent com ...

2021

Optical-Microwave Pump-Probe Studies of Electronic Properties in Novel Materials

Karoly Holczer, Ferenc Simon, András Bojtor, Sándor Kollarics, Bence Gábor Márkus

Combined microwave-optical pump-probe methods are emerging to study the quantum state of spin qubit centers and the charge dynamics in semiconductors. A major hindrance is the limited bandwidth of microwave irradiation/detection circuitry which can be over ...

WILEY-V C H VERLAG GMBH2020

High-Performance n-type SnSe Thermoelectric Polycrystal Prepared by Arc-Melting

Ferenc Simon, Bence Gábor Márkus

Tin selenide (SnSe) has notable thermoelectric properties, yet stable n-type polycrystalline SnSe is difficult to synthesize. Here, polycrystalline SnSe is easily prepared by arc-melting as robust pellets, with thermoelectric properties repeatably changing ...

2020

Incidence of Quantum Confinement on Dark Triplet Excitons in Carbon Nanotubes

Ferenc Simon

The photophysics of single-wall carbon nanotubes (SWCNTs) is intensively studied due to their potential application in light harvesting and optoelectronics. Excited states of SWCNTs form strongly bound electron-hole pairs, excitons, of which only singlet e ...

2020

Entropy in Spin Relaxation, Spintronics, and Magnetic Resonance

Ferenc Simon

The entropy change during spin relaxation for a realistic model system is studied, whose spin dynamics can be handled with the Boltzmann equation. The time evolution of the von Neumann entropy is monitored during the process and is compared with the recent ...

WILEY-V C H VERLAG GMBH2020

Tuning Conductivity and Spin Dynamics in Few-Layer Graphene via In Situ Potassium Exposure

László Forró, Bálint Náfrádi, Péter Szirmai, Olivér Sági, Ferenc Simon, Sándor Kollarics, Bence Gábor Márkus

Chemical modification such as intercalation or doping of novel materials is of great importance for exploratory material science and applications in various fields of physics and chemistry. Herein, the systematic intercalation of chemically exfoliated few- ...

2020

Generic phase diagram of spin relaxation in solids and the Loschmidt echo

Ferenc Simon

The spin relaxation time in solids is determined by several competing energy scales and processes, and distinct methods are called for to analyze the various regimes. We present a stochastic model for the spin dynamics in solids which is equivalent to solv ...

AMER PHYSICAL SOC2020

Improved Alkali Intercalation of Carbonaceous Materials in Ammonia Solution

László Forró, Bálint Náfrádi, Péter Szirmai, Ferenc Simon, Sándor Kollarics, Bence Gábor Márkus

Alkali-intercalated graphite compounds represent a compelling modification of carbon with significant application potential and various fundamentally important phases. The intercalation of graphite with alkali atoms (Li and K) using liquid ammonia solution ...

WILEY-V C H VERLAG GMBH2019

Characterizing the maximum number of layers in chemically exfoliated graphene

László Forró, Bálint Náfrádi, Péter Szirmai, Julian Ayrton Englert, Ferenc Simon, Bence Gábor Márkus

An efficient route to synthesize macroscopic amounts of graphene is highly desired and bulk characterization of such samples, in terms of the number of layers, is equally important. We present a Raman spectroscopy-based method to determine the typical uppe ...

Springer Nature2019

Anisotropic Elliott-Yafet theory and application to KC8 potassium intercalated graphite

László Forró, Bálint Náfrádi, Péter Szirmai, Ferenc Simon, Bence Gábor Márkus

We report electron spin resonance (ESR) measurements on stage-I potassium intercalated graphite (KC8). Angular dependent measurements show that the spin-lattice relaxation time is longer when the magnetic field is perpendicular to the graphene layer as com ...

Wiley-V C H Verlag Gmbh2016

Observation of conduction electron spin resonance in boron-doped diamond

László Forró, Bálint Náfrádi, Péter Szirmai, Ferenc Simon

We observe the electron spin resonance of conduction electrons in boron-doped (6400 ppm) superconducting diamond (T-c = 3.8 K). We clearly identify the benchmarks of conduction electron spin resonance (CESR): the nearly temperature independent electron spi ...

Amer Physical Soc2013

On the low temperature microwave absorption anomaly in single-wall carbon nanotubes

László Forró, Ferenc Simon

The low temperature microwave absorption anomaly reported by Corzilius et al. [Phys. Rev. B 75, 235416 (2007)] in single-wall carbon nanotubes (SWCNTs) is revisited. It was originally reported that the microwave absorption of CVD grown SWCNTs shows an unex ...

Wiley-V C H Verlag Gmbh2012

Density of states deduced from ESR measurements on low-dimensional nanostructures; benchmarks to identify the ESR signals of graphene and SWCNTs

László Forró, Péter Szirmai, Ferenc Simon

Electron spin resonance (ESR) spectroscopy is an important tool to characterize the ground state of conduction electrons and to measure their spin-relaxation times. Observing ESR of the itinerant electrons is thus of great importance in graphene and in sin ...

2011