48 research outputs found
Magnetic and defect probes of the SmB surface state
The impact of non-magnetic and magnetic impurities on topological insulators
is a central problem concerning their fundamental physics and possible novel
spintronics and quantum computing applications. SmB, predicted to be a
topological Kondo insulator, is considered a benchmark material. Using a
spin-polarized tip in scanning tunneling spectroscopy destroys the signature
peak of the topological surface state, revealing its spin texture. Further,
combining local STS with macroscopic transport measurements on SmB
containing different substitutions enables us to investigate the effect of
impurities. The surface states around impurities are locally suppressed with
different length scales depending on their magnetic properties and, for
sufficiently high impurity level, globally destroyed. Our study points directly
to the topological nature of SmB, and unveils, microscopically and
macroscopically, how impurities -- magnetic or non-magnetic -- affect
topological surface states
Recent progress on superconductors with time-reversal symmetry breaking
Superconductivity and magnetism are antagonistic states of matter. The presence of spontaneous magnetic fields inside the superconducting state is, therefore, an intriguing phenomenon prompting extensive experimental and theoretical research. In this review, we discuss recent experimental discoveries of unconventional superconductors which spontaneously break time-reversal symmetry and theoretical efforts in understanding their properties. We discuss the main experimental probes and give an extensive account of theoretical approaches to understand the order parameter symmetries and the corresponding pairing mechanisms including the importance of multiple bands
Synthesis and physical properties of CeRhSb single crystals
Millimeter-sized CeRhSb () single
crystals were synthesized by a Bi-flux method and their physical properties
were studied by a combination of electrical transport, magnetic and
thermodynamic measurements. The resistivity anisotropy
, manifesting a quasi-one-dimensional electronic
character. Magnetic susceptibility measurements confirm as the
magnetic easy plane. A long-range antiferromagnetic transition occurs at
K, while clear short-range ordering can be detected well above .
The low ordering temperature is ascribed to the large Ce-Ce distance as well as
the geometric frustration. Kondo scale is estimated to be about 2.4 K,
comparable to the strength of magnetic exchange. CeRhSb,
therefore, represents a rare example of dense Kondo lattice whose
Ruderman-Kittel-Kasuya-Yosida exchange and Kondo coupling are both weak but
competing.Comment: 7 pages, 4 figures, 2 table
Anisotropic c-f hybridization in the ferromagnetic quantum critical metal CeRhGe
Heavy fermion compounds exhibiting a ferromagnetic quantum critical point
have attracted considerable interest. Common to two known cases, i.e.,
CeRhGe and YbNiP, is that the 4f moments reside along chains
with a large inter-chain distance, exhibiting strong magnetic anisotropy that
was proposed to be vital for the ferromagnetic quantum criticality. Here we
report an angle-resolved photoemission study on CeRh6Ge4, where we observe
sharp momentum-dependent 4f bands and clear bending of the conduction bands
near the Fermi level, indicating considerable hybridization between conduction
and 4f electrons. The extracted hybridization strength is anisotropic in
momentum space and is obviously stronger along the Ce chain direction. The
hybridized 4f bands persist up to high temperatures, and the evolution of their
intensity shows clear band dependence. Our results provide spectroscopic
evidence for anisotropic hybridization between conduction and 4f electrons in
CeRhGe, which could be important for understanding the electronic
origin of the ferromagnetic quantum criticality