Nonlinear optical spectroscopies are powerful tools for investigating both static material
properties and light-induced dynamics. Terahertz (THz) emission spectroscopy has …

Helical spin structures are expressions of magnetically induced chirality, entangling the
dipolar and magnetic orders in materials,,–. The recent discovery of helical van der Waals …

Broken symmetries and electronic topology are well manifested together in the second-order
nonlinear optical responses from topologically non-trivial materials. Although second-order …

Chiral crystals, characterized by rotation, screw rotation, and translation symmetries are
abundant in nature. The existence of Kramers–Weyl fermions (KWFs) at the time‐reversal …

Chiral multifold fermions are quasiparticles that appear only in chiral crystals such as
transition metal silicides in the cubic B20 structure (ie, the CoSi family), and they may show …

Semiconducting monolayer Mo Si 2 N 4 and monolayer WSi 2 N 4 have recently been
fabricated and a number of two-dimensional (2D) materials with the same chemical formula …

Topological insulators and Weyl semimetals have demonstrated a helicity-dependent
photocurrent (HDPC). In contrast, Dirac semimetals (DSMs) possess chirality-degenerate …

Novel topological phases of matter are fruitful platforms for the discovery of unconventional
electromagnetic phenomena. Higher-fold topology is one example, where the low-energy …

Nonlinear optical spectroscopy is a fundamental probe for the investigation of topological
effects in quantum materials. In this paper, we report on the terahertz (THz) emission from …

One of the most striking signatures of Weyl fermions is their surface Fermi arcs. Less known
is that Fermi arcs can also be localized at internal twin boundaries where two Weyl materials …