Ahmet Avsar

@article{ISI:001620530800035,
title = {Electric field-tunable ferromagnetism in a van der Waals semiconductor up to room temperature},
author = {Deyi Fu and Jiawei Liu and Fuchen Hou and Xiao Chang and Tingyu Qu and Johan Felisaz and Gunasheel Kauwtilyaa Krishnaswamy and Sergey Grebenchuk and Yuang Jie and Kenji Watanabe and Takashi Taniguchi and Vitor M Pereira and Kostya S Novoselov and Maciej Koperski and Nikolai L Yakovlev and Anjan Soumyanarayanan and Ahmet Avsar and Oleg V Yazyev and Junhao Lin and Barbaros Ozyilmaz},
doi = {10.1038/s41467-025-59961-2},
times_cited = {0},
year = {2025},
date = {2025-11-20},
journal = {NATURE COMMUNICATIONS},
volume = {16},
number = {1},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {Ferromagnetic semiconductors, coupling charge transport and magnetism via electrical means, show great promise for spin-based logic devices. Despite decades of efforts to achieve such co-functionality, maintaining ferromagnetic order at room temperature remains elusive. Here, we address this long-standing challenge by implanting dilute Co atoms into few-layer black phosphorus through atomically-thin boron nitride diffusion barrier. Our Co-doped black phosphorus-based devices exhibit ferromagnetism up to room temperature while preserving its high mobility (similar to 1000cm(2)V(-1)s(-1)) and semiconducting characteristics. By incorporating ferromagnetic Co-doped black phosphorus into magnetic tunnel junction devices, we demonstrate a large tunnelling magnetoresistance that extends up to room temperature. This study presents a new approach to engineering ferromagnetic ordering in otherwise nonmagnetic materials, thereby expanding the repertoire and applications of magnetic semiconductors envisioned thus far.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001581804400001,
title = {Reconfigurable Magnetotransport in MnBi2Te4 via Gate and Magnetic Field Tuning},
author = {Yuang Jie and Xiaofan Cai and Yijie Lin and Kenji Watanabe and Takashi Taniguchi and Jiaqiang Yan and Dmitry Ovchinnikov and Ahmet Avsar},
doi = {10.1002/adma.202510734},
times_cited = {0},
issn = {0935-9648},
year = {2025},
date = {2025-09-26},
journal = {ADVANCED MATERIALS},
volume = {37},
number = {50},
publisher = {WILEY-V C H VERLAG GMBH},
address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY},
abstract = {The intrinsic magnetic topological insulator MnBi2Te4 is a promising platform for exploring quantum phases with nontrivial band topology and for enabling electrical control over coupled magnetic and electronic phase transitions. In-plane magnetic fields, in particular, offer a distinct means of tuning these properties by strengthening quantized Hall effects, enhancing surface energy gaps, and driving spin reorientation transitions. However, a systematic understanding of how such fields affect magnetotransport is limited. Here, the magnetotransport behavior of few-layer MnBi2Te4 as a function of gate voltage, temperature, and magnetic field angle, with a primary focus on in-plane field effects, are investigated. A gate-tunable crossover in magnetoresistance is observed from positive to negative values under in-plane magnetic fields as the gate voltage is swept below the charge neutrality point at temperatures below the N & eacute;el temperature. The in-plane field drives a transition from the antiferromagnetic ground state to a ferromagnetic configuration with spins aligned in-plane, while simultaneously altering the electronic structure, as revealed by gate-dependent transport features. The angle-dependent measurements reveal strongly gate-tunable magnetotransport anisotropy. These results establish in-plane magnetic fields as an effective tuning parameter for modulating spin and charge transport in MnBi2Te4, advancing prospects for reconfigurable spintronic and topological devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001461986000001,
title = {Novel spintronic effects in two-dimensional van der Waals heterostructures},
author = {Zhiyuan Zhao and Yijie Lin and Ahmet Avsar},
doi = {10.1038/s41699-025-00546-4},
times_cited = {6},
year = {2025},
date = {2025-04-09},
journal = {NPJ 2D MATERIALS AND APPLICATIONS},
volume = {9},
number = {1},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {Precise engineering of spin interfaces is essential for the development of spintronic devices. Two-dimensional vdW heterostructures enable atomically sharp interfaces that facilitate exploration of fundamental spin phenomena. Moreover, the discovery of two-dimensional magnetic materials has accelerated the field, leading to novel devices and spin effects. This review highlights recent advancements in vdW interfacial spin physics, innovative device structures, and emerging moir & eacute;-induced topological effects, with implications for future spintronic applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001142010100002,
title = {Highly anisotropic spin transport in ultrathin black phosphorus},
author = {Luke Cording and Jiawei Liu and Jun You Tan and Kenji Watanabe and Takashi Taniguchi and Ahmet Avsar and Barbaros Ozyilmaz},
doi = {10.1038/s41563-023-01779-8},
times_cited = {30},
issn = {1476-1122},
year = {2024},
date = {2024-01-12},
journal = {NATURE MATERIALS},
volume = {23},
number = {4},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {In anisotropic crystals, the direction-dependent effective mass of carriers can have a profound impact on spin transport dynamics. The puckered crystal structure of black phosphorus leads to direction-dependent charge transport and optical response, suggesting that it is an ideal system for studying anisotropic spin transport. To this end, we fabricate and characterize high-mobility encapsulated ultrathin black-phosphorus-based spin valves in a four-terminal geometry. Our measurements show that in-plane spin lifetimes are strongly gate tunable and exceed one nanosecond. Through high out-of-plane magnetic fields, we observe a fivefold enhancement in the out-of-plane spin signal case compared to in-plane and estimate a colossal spin-lifetime anisotropy of similar to 6. This finding is further confirmed by oblique Hanle measurements. Additionally, we estimate an in-plane spin-lifetime anisotropy ratio of up to 1.8. Our observation of strongly anisotropic spin transport along three orthogonal axes in this pristine material could be exploited to realize directionally tunable spin transport.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}