282 citations · 1.4k across the 24 of their papers we have counts for
25 papers
Magnetic proximity beyond the interface: Layer-sequence-dependent exchange in WSe/CrI heterostructures
Natalie Kuhn, Marc Schütte, Joachim Emming +8
Magnetic proximity effects in transition metal dichalcogenide (TMD)/2D-magnet heterostructures are often described in terms of the magnetization of the interfacial magnetic layer.…
Gate-tunable Josephson diodes in magic-angle twisted bilayer graphene
A. Rothstein, R. J. Dolleman, L. Klebl +8
We report low-temperature measurements of two adjacent, gate-defined Josephson junctions (JJs) in magic-angle twisted bilayer graphene (MATBG) at a moiré filling factor near $ν= -2…
Room-temperature spin-lifetime anisotropy exceeding 60 in bilayer graphene spin valves proximity coupled to WSe
Timo Bisswanger, Anne Schmidt, Frank Volmer +2
A spin lifetime anisotropy between in-plane and out-of-plane spins in bilayer graphene (BLG) can be achieved by spin-orbit proximity coupling of graphene to transition metal dichal…
Current-induced brightening of vacancy-related emitters in hexagonal boron nitride
Corinne Steiner, Rebecca Rahmel, Frank Volmer +9
We perform photoluminescence measurements on vacancy-related emitters in hexagonal boron nitride (hBN) that are notorious for their low quantum yields. The gating of these emitters…
Twist angle dependent interlayer transfer of valley polarization from excitons to free charge carriers in WSe/MoSe heterobilayers
Frank Volmer, Manfred Ersfeld, Paulo E. Faria Junior +13
We identify an optical excitation mechanism that transfers a valley polarization from photo-excited electron-hole pairs to free charge carriers in twisted WSe/MoSe heterobi…
Transport spectroscopy of ultraclean tunable band gaps in bilayer graphene
E. Icking, L. Banszerus, F. Wörtche +11
The importance of controlling both the charge carrier density and the band gap of a semiconductor cannot be overstated, as it opens the doors to a wide range of applications, inclu…
Charge-induced artifacts in non-local spin transport measurements: How to prevent spurious voltage signals
F. Volmer, T. Bisswanger, A. Schmidt +2
To conduct spin-sensitive transport measurements, a non-local device geometry is often used to avoid spurious voltages that are caused by the flow of charges. However, in the vast…
CVD bilayer graphene spin valves with 26 m spin diffusion length at room temperature
T. Bisswanger, Z. Winter, A. Schmidt +5
We present inverted spin-valves fabricated from CVD-grown bilayer graphene (BLG) that show more than a doubling in device performance at room temperature compared to state-of-the a…
How to solve problems in micro- and nanofabrication caused by the emission of electrons and charged metal atoms during e-beam evaporation
Frank Volmer, Inga Seidler, Timo Bisswanger +4
We discuss how the emission of electrons and ions during electron-beam-induced physical vapor deposition can cause problems in micro- and nanofabrication processes. After giving a…
Valley lifetimes of conduction band electrons in monolayer WSe
Manfred Ersfeld, Frank Volmer, Lars Rathmann +10
One of the main tasks in the investigation of 2-dimensional transition metal dichalcogenides is the determination of valley lifetimes. In this work, we combine time-resolved Kerr r…
How the dynamic of photo-induced gate screening complicates the investigation of valley physics in 2D materials
F. Volmer, M. Ersfeld, L. Rathmann +6
An in-depth analysis of valley physics in 2D materials like transition metal dichalcogenides requires the measurement of many material properties as a function of Fermi level posit…
Unveiling valley lifetimes of free charge carriers in monolayer WSe
Manfred Ersfeld, Frank Volmer, Lars Rathmann +10
We report on nanosecond long, gate-dependent valley lifetimes of free charge carriers in monolayer WSe, unambiguously identified by the combination of time-resolved Kerr rotati…
Non-local electrical detection of spin-polarized surface currents in the 3D topological insulator BiSbTeSe
Shaham Jafarpisheh, Frank Volmer, Zhiwei Wang +4
The spin-polarized surface states in topological insulators offer unique transport characteristics that make them distinguishable from trivial conductors. Here, we detect the impac…
Dry-transferred CVD graphene for inverted spin valve devices
Marc Drögeler, Luca Banszerus, Frank Volmer +4
Integrating high-mobility graphene grown by chemical vapor deposition (CVD) into spin transport devices is one of the key tasks in graphene spintronics. We use a van der Waals pick…
Spin States Protected from Intrinsic Electron-Phonon-Coupling Reaching 100 ns Lifetime at Room Temperature in MoSe
Manfred Ersfeld, Frank Volmer, Pedro Miguel M. C. de Melo +6
We present time-resolved Kerr rotation measurements, showing spin lifetimes of over 100 ns at room temperature in monolayer MoSe. These long lifetimes are accompanied by an int…
Simulations on the influence of spatially-varying spin transport parameters on the measured spin lifetime in graphene non-local spin valves
Marc Drögeler, Frank Volmer, Christoph Stampfer +1
Spin transport properties of graphene non-local spin valve devices are typically determined from Hanle spin precession measurements by using a simplified solution of the one-dimens…
Spin lifetimes exceeding 12 nanoseconds in graphene non-local spin valve devices
Marc Drögeler, Christopher Franzen, Frank Volmer +7
We show spin lifetimes of 12.6 ns and spin diffusion lengths as long as 30.5 μm in single layer graphene non-local spin transport devices at room temperature. This is accomplished…
Nanosecond spin lifetimes in bottom-up fabricated bilayer graphene spin-valves with atomic layer deposited AlO spin injection and detection barriers
Marc Drögeler, Frank Volmer, Maik Wolter +5
We present spin transport studies on bi- and trilayer graphene non-local spin-valves which have been fabricated by a bottom-up fabrication method. By this technique, spin injection…
Spin and charge transport in graphene-based spin transport devices with Co/MgO spin injection and spin detection electrodes
F. Volmer, M. Drögeler, G. Güntherodt +2
In this review we discuss spin and charge transport properties in graphene-based single-layer and few-layer spin-valve devices. We give an overview of challenges and recent advance…
Contact-induced charge contributions to non-local spin transport measurements in Co/MgO/graphene devices
F. Volmer, M. Drögeler, T. Pohlmann +3
Recently, it has been shown that oxide barriers in graphene-based non-local spin-valve structures can be the bottleneck for spin transport. The barriers may cause spin dephasing du…
Suppression of contact-induced spin dephasing in graphene/MgO/Co spin-valve devices by successive oxygen treatments
F. Volmer, M. Drögeler, E. Maynicke +5
By successive oxygen treatments of graphene non-local spin-valve devices we achieve a gradual increase of the contact resistance area products () of Co/MgO spin injection and…
Nanosecond spin lifetimes in single- and few-layer graphene-hBN heterostructures at room temperature
Marc Drögeler, Frank Volmer, Maik Wolter +6
We present a new fabrication method of graphene spin-valve devices which yields enhanced spin and charge transport properties by improving both the electrode-to-graphene and graphe…
Role of MgO barriers for spin and charge transport in Co/MgO/graphene non-local spin-valve devices
F. Volmer, M. Drögeler, E. Maynicke +4
We investigate spin and charge transport in both single and bilayer graphene non-local spin-valve devices. Similar to previous studies on bilayer graphene, we observe an inverse de…
Towards wafer scale fabrication of graphene based spin valve devices
Ahmet Avsar, Tsung-Yeh Yang, Su-Kang Bae +9
We demonstrate injection, transport and detection of spins in spin valve arrays patterned in both copper based chemical vapor deposition (Cu-CVD) synthesized wafer scale single lay…