Welcome!
We are a theory group investigating magnetic, phononic, and quantum hybrid systems, with a focus on the interplay between their topological properties, dissipation, and quantum many-body dynamics. A significant part of our current research lies at the intersection between condensed matter physics, quantum optics and quantum information science.
Our approach involves analytical and numerical methods and frequent collaborations with experimental groups.
Recent News
3/2024: I gave an invited talk titled “Phonon chirality and thermal Hall transport" at the DPG Meeting in Berlin.
2/2024: I gave a colloquium titled “A solid-state platform for cooperative quantum phenomena" at UC, Riverside. Thank you Igor for the invitation!
1/2024: I gave a colloquium titled “A solid-state platform for cooperative quantum phenomena" at CUNY. Thank you So for the invitation!
12/2023: I gave a talk on “Non-Hermitian Physics in Magnetic Systems" at online Seminars on non-Hermitian Physics.
10/2023: I gave a talk on "“The Non-Hermitian Skin Effect in Magnetic Systems" at the Latin American Workshop on Magnetism, Magnetic Materials & their Applications in Puerto Varas, Chile.
10/2023: I gave a talk titled "A Solid-State Platform for Cooperative Quantum Phenomena" at the Quantum Vacuum in Materials International Workshop at Rice University.
8/2023: I gave a talk on "The Non-Hermitian Skin Effect in Magnetic Systems" at the workshop on Non-Hermitian Topology: from Classical Optics to Quantum Matter in Dresden, Germany.
7/2023: I gave a talk on "Charge Defects and Phonon Hall effects in Ionic Crystals" at CECAM Workshop: Chiral Phonons in Quantum Materials in Lugano, Switzerland.
5/2023: I gave a talk on "The Non-Hermitian Skin Effect" at Spin Caloritronics XII in Tsukuba, Japan.
5/2023: I gave a talk on "The Non-Hermitian Skin Effect" at the TopoMag23 workshop in Columbus, Ohio. Thanks for the invitation Yuanming and Jos!
4/2023: Our Guest Editorial Advances in Magnonics introducing this special topic collection is out on Journal of Applied Physics!
4/2023: I gave a talk on "Dissipation in quantum hybrid and classical spin systems" at the group seminary of Thore Posske, who is hosting me in Hamburg as the 2022 Mildred Dresselhaus Junior Guest Professor.
4/2023: I gave a talk at the QuCoLiMa (Quantum Cooperativity of Light and Matter) seminars on "Dissipation in quantum hybrid and classical spin systems". Thank you for invitation Jamir!
3/2023: We are still accepting applications for our SPICE workshop Quantum Spinoptics! This workshop aims at the interdisciplinary experiment of bringing together experts from solid state and quantum optics, in order to foster dialogue at the interface of the two communities.
3/2023: Our paper Exceptional points as signatures of dynamical magnetic phase transitions is out as Letter on PRB. In this work, we show that there is a direct relation between the emergence of exceptional points in the linearized coupled magnetization dynamics and the emergence of dynamical phase transitions in the non-linear Landau-Lifshitz-like magnetization dynamics.
2/2023: I gave two seminar, one at USC and one at UCLA, on "Dissipation in Magnetic and Quantum Hybrid Spin Systems". Thanks for the great visits everyone!
1/2023: Our paper Magnon-magnon interactions induced by spin pumping-driven symmetry breaking in synthetic antiferromagnets is out! In this experimental/theoretical collaboration, we expand the phenomenology of spin pumping to noncollinear magnetization configurations and uncover a novel spin pumping-driven symmetry-breaking mechanism.
12/2022: I gave an invited talk at the Spin Cavitronics IV Workshop on "Engineering dynamical and topological phase transition from a non-Hermitian perspective".
12/2022: I am really happy to announce that I was awarded the Mildred Dresselhaus Award 2022.
10/2022: Thore Posske, Mircea Trif and I are organizing the Northern Lights Conference 2022 on the interplay between topology, spin systems, and superconductivity. The conference will be held in person at the National Museum of Iceland, in the heart of Reykjavík.
We have secured 32 invited speakers, but we have still few slots available for contributed talks and poster presentations: you are welcome to apply for one on them on our website!
10/2022: I gave a online talk titled "Exceptional points as signatures of topological and dynamical phase transitions of the magnetization dynamics" at the IEEE Magnetics Society Italy Chapter workshop. Thanks for the invitation Giovanni!
10/2022: I I gave a seminar titled "New phenomena in dissipative magnetic systems" at the UCCS. Thanks for the great visit Ezio and Dima!
9/2022: Our Perspective on non-Hermitian physics in magnetic systems is out! In this work, we review the progress resulting from applying non-Hermitian theories to the dynamics of both pure and hybrid magnonic systems, and we offer our perspective on future research.
8/2022: I gave an invited talk at the Magnonics 2022 workshop on "Unveiling new phenomena in dissipative magnetic systems".
7/2022: Our paper Multitude of exceptional points in van der Waals bilayers is out! In this work, we show that layered 2d magnets driven by spin current injection can host a multitude of EPs, which can likely influence the response functions routinely probed in spintronics setups. Furthermore, we unveil a peculiar k-dependent pseudo-Hermiticity and topological insulating phases analogous to the model's Hermitian counterpart.
7/2022: Our paper Topological magnetic phase transition in Eu-based A-type antiferromagnets is out! Recently, a colossal magnetoresistance (CMR) was observed in a Eu-based compound that does not fit the conventional mixed-valence paradigm. In previous work, we suggested a magnetic BKT transition as the mechanism underlying the dramatic increase in the temperature-dependence magnetoresistance. In this work, using Montecarlo techniques, we explore the magnetic phases of Eu-based A-type antiferromagnets and provide qualitative numerical evidence that the effect can be related to a magnetic BKT transition.
6/2022: I gave a talk titled "New phenomena in dissipative magnetic systems" at the Sol-SkyMag 2022 Conference in San Sebastian.
6/2022: I gave a seminar titled "New phenomena in dissipative magnetic systems" at La Sorbonne University in Paris. Thanks for the great visit Massimiliano!
5/2022: Our paper The phonon Hall viscosity of ionic crystals is out! In this work, we show every ionic crystal in a magnetic field has a sizable Hall viscosity, independent of phonon coupling to external degrees of freedom.
5/2022: I gave an invited talk at the Spin Caloritronics 2022 conference in Urbana-Champaign on new phenomena in dissipative magnetic systems.
5/2022: I gave an invited talk at the 2022 MRS Spring Meeting in Honolulu on topological phases in dissipative magnetic systems.
5/2022: Our paper Exceptional points as a route to magnetic nano-oscillators is out! In this work, we investigate the interplay between linear and nonlinear spin dynamics in proximity of exceptional points.
4/2022: I gave an (online) talk at Manchester University on topological phenomena in dissipative systems. Thanks Angelika for the invitation!
3/2022: I gave an invited talk at the 2022 March Meeting titled "Charged defects and phonon Hall effects in ionic crystals". The giant thermal Hall conductivities measured recently in dielectric oxides with different crystalline structures and unalike magnetic and ferroelectric orders (or lack of thereof) are a truly fascinating puzzle. If you are interested, here a link to our proposed theoretical interpretation of these signals. Thanks to Louis for organizing this APS session!
2/2022: I am really happy to announce that our application to host the APS Conference for Undergraduate Women in Physics in 2024 at Boston College, in partnership with Wellesley College, has been accepted!
2/2022: This year I have coordinated the inclusion of the physics department into the Women in Science program at Boston College. This initiative targets female students from Boston-area high schools, with the goal of sparking their interest in science at an early age and of introducing them to female role models. Many thanks to Alenna, Bryan, and Faranak who have served as volunteers in our event and to all the help provided by Malavika.
1/2022: Our paper Non-linear dynamics of the non-Hermitian Su-Schrieffer-Heeger model is out! In this work, we investigate the non-linear and finite-temperature dynamics of a spin-torque oscillator array that realizes a non-Hermitian topological phase. Our results show that the topologically-protected lasing edge mode dynamics can persist for a broad range of temperatures and parameters.
1/2022: I gave an in-person seminar titled "Magnetic topological phases in dissipative systems" at Ohio State University. Thanks for the wonderful visit Jos and Yuanming!
1/2022: Our paper Noninvasive measurements of spin transport properties of an antiferromagnetic insulator has been published on Science Advances!
12/2021: Our Women in Physics Group at Boston College has been awarded an APS WiP Group Grant!
12/2021: I am really happy to announce that I was awarded the NSF CAREER award! This grant offers us continuing support (2022-2027) for our research on Magnetic topological phases in dissipative systems.
9/2021: I gave a seminar titled "Magnetic topological phases in dissipative systems " at Columbia University. Thanks for the invitation!
9/2021: I gave a talk titled "Magnon-polarons in magnetic insulators" at the Virtual DPG Meeting “SKM21”. In this talk, I discuss the effects of strong magneto-elastic coupling on the transport properties of magnetic insulators and show that the sharp structures in magnetic field-dependent spin Seebeck effect (SSE) voltages observed Pt/YIG at low temperatures can be attributed to the magnon-phonon interaction. For more details, click here.
9/2021: Our paper "Non-Hermitian skin effect in magnetic systems" is out! In this work, we show that the non-Hermitian skin effect, whose emergence is in two- or higher-dimensional solid-state systems remains largely unexplored, can appear in a van der Waals magnetic monolayer in a magnetic system due to intrinsic spin-spin and spin-phonon interactions. Moreover, we propose a guiding principle to predict the emergence of the skin effect and its dependence on the system’s parameters. For more details, click here.
9/2021: I gave a talk titled "Magnetic topological phases in dissipative systems " at the on-line SPICE-SPIN+X spintronics seminars. In this talk, I discuss how the recent introduction of non-Hermitian topological classifications has opened up opportunities for engineering topological phases in magnetic systems, and I present our first proposal of a non-Hermitian topological magnonic system. Furthermore, I discuss the conditions under which magnetic insulating systems can host one of the most striking non-Hermitian phenomena with no Hermitian counterpart, i.e., the skin effect, which underlies the breakdown of the bulk-edge correspondence. For the video, click here.
9/2021: Our NGP collaboration focused on MonteCarlo simulations of spin systems with the group of Thore Posske has officially started.
8/2021: This fall semester I will be teaching the graduate-level class "Topology in condensed matter".
8/2021: We had our first social meeting for female undergraduate and graduate students at Boston College! If you want to join, we will be meeting every first Monday of the month at 5pm.
I am currently searching for undergraduates that would like to join with me the initiative Women in Science at Boston College. This initiative targets female students from Boston-area high schools, with the goal of sparking their interest in science at an early age and of introducing them to potential female role models in science. If you are interested in discussing more, drop by my office or send me an email at flebus@bc.edu.
8/2021: Our paper "Spin interactions and topological magnonics in chromium trihalide CrClBrI" is out! Recently, experimental work has shown the discrete lattice symmetry and degree of anisotropy of spin-spin interactions in chromium halides can be tuned by changing the relative composition of halide atoms. Motivated by this advancement, here we derive a model chromium trihalide CrClBrI. For more details, click here.
7/2021: Our paper "Charged Defects and Phonon Hall Effects in Ionic Crystals" is out! Recently the striking observation of giant thermal Hall signals in many insulating oxides, including high-temperature superconductors, has stimulated great interest. While it is clear now that phonons are the main heat carriers, the mechanism responsible for the enhanced magnitude of the thermal Hall signal at high magnetic fields remains puzzling. Up to now, most theoretical proposals that have addressed this puzzle rely on the coupling of phonons to a surrounding spin or electronic environment. In this work, we propose an alternative mechanism based on phonon scattering on extrinsic impurities that break time-reversal symmetry. For more details, click here.
7/2021: Our paper "Magnetoresistance driven by the magnetic Berezinskii-Kosterlitz-Thouless transition" has been accepted for publication! Recently, a temperature-dependent colossal magnetoresistance was measured in the antiferromagnetic EuCd2P2. Motivated by this experimental discovery, in this work we investigate the interplay between electronic and magnetic degrees of freedom near the BKT transition and we show that a colossal magnetoresistance is consistent with an exponential proliferation of topological defects. For more details, click here.
6/2021: I gave a talk titled "Entangling Distant Spin qubits via a Magnetic Domain Wall" at NSF Virtual Workshop on Emerging Opportunities at the Intersection of Quantum and Thermal Sciences. In this talk, I discuss a scheme to entangle distant spin qubits, such as NV centers, via the soft modes of an antiferromagnetic domain wall. For more details on this proposal, click here.
4/2021: Our review "Magnonics in collinear magnetic insulating systems" has been promoted to a Featured Article in the Journal of Applied Physics! In this work, we provide a pedagogical introduction to theoretical and experimental advances in the study of magnonics in collinear magnetic insulating systems. For more details, click here.
3/2021: I gave an online CMT Kids' Seminar at Harvard University, titled "Unveiling new phenomena in magnetic systems".
1/2021: I gave an online Seminar at Aachen University, titled "Unveiling new phenomena in magnetic systems".
1/2021: Our paper "Floquet engineering of topological transitions in a twisted transition metal dichalcogenide homobilayer" has been chosen as Editor's Suggestions in Phys. Rev. B! In this work, we study twisted transition metal dichalcogenide bilayers driven by different forms of monochromatic light. For more details, click here.
11/2020: Our paper "Quantum Sensing of Spin Transport Properties of an Antiferromagnetic Insulator" is out! This theoretical/experimental collaboration shows the potential of NV centers in diagnosing spin transport properties in a broad range of high-frequency magnetic materials, which are challenging to access by more conventional measurement techniques. For more details, click here.
11/2020: I gave a talk titled "Non-Hermitian topology of 1D spin-torque oscillators arrays" at the SPICE workshop on Coherent order and spin transport in spin-active systems. In this talk, I present our first proposal of a non-Hermitian topological magnonic system. For the video, click here..
9/2020: I have officially started an Assistant Professor position at Boston College! This semester I will teach the graduate-level course "Topology in Condensed Matter". 20s20