4 research outputs found
Topological magnon-photon interaction for cavity magnonics
The study of cavity magnonics and topological insulators has made significant
advances over the past decade, however the possibility of combining the two
fields is still unexplored. Here, we explore such connection by investigating
hybrid cavity systems that incorporate both a ferromagnet and a topological
insulator. We find that electrons in the topological surface state efficiently
mediate the effective electric dipole coupling between the spin of the
ferromagnet and the electric field of the cavity, in contrast with the
conventional cavity magnonics theory based on magnetic dipole coupling. We
refer to this coupling as topological magnon-photon interaction, estimating it
one order of magnitude stronger than the conventional magnon-photon coupling,
and showing that its sign can be manipulated. We discuss the potential of our
proposed device to allow for scaling down and controlling the cavity system
using electronics. Our results provide solid ground for exploring the
functionalities enabled by merging cavity magnonics with topological
insulators.Comment: 8 pages, 2 figures, Accepted version to Communications Physic
Cavity magnonics with easy-axis ferromagnet: critically enhanced magnon squeezing and light-matter interaction
Generating and probing the magnon squeezing is an important challenge in the
field of quantum magnonics. In this work, we propose a cavity magnonics setup
with an easy-axis ferromagnet to address this challenge. To this end, we first
establish a mechanism for the generation of magnon squeezing in the easy-axis
ferromagnet and show that the magnon squeezing can be critically enhanced by
tuning an external magnetic field near the Ising phase transition point. When
the magnet is coupled to the cavity field, the effective cavity-magnon
interaction becomes proportional to the magnon squeezing, allowing one to
enhance the cavity-magnon coupling strength using a static field. We
demonstrate that the magnon squeezing can be probed by measuring the frequency
shift of the cavity field. Moreover, a magnonic superradiant phase transition
can be observed in our setup by tuning the static magnetic field, overcoming
the challenge that the magnetic interaction between the cavity and the magnet
is typically too weak to drive the superradiant transition. Our work paves the
way to develop unique capabilities of cavity magnonics that goes beyond the
conventional cavity QED physics by harnessing the intrinsic property of a
magnet.Comment: 7 pages, 2 figure
Non-Fermi Liquids in Conducting Two-Dimensional Networks
We explore the physics of novel fermion liquids emerging from conducting networks, where 1D metallic wires form a periodic 2D superstructure. Such structure naturally appears in marginally twisted bilayer graphenes, moire transition metal dichalcogenides, and also in some charge-density wave materials. For these network systems, we theoretically show that a remarkably wide variety of new non-Fermi liquids emerge and that these non-Fermi liquids can be classified by the characteristics of the junctions in networks. Using this, we calculate the electric conductivity of the non-Fermi liquids as a function of temperature, which show markedly different scaling behaviors than a regular 2D Fermi liquid.11Nsciescopu