2,452 research outputs found
Questing for Algebraic Mass Dimension One Spinor Fields
This work deals with new classes of spinors of mass dimension one in
Minkowski spacetime. In order to accomplish it, the Lounesto classification
scheme and the inversion theorem are going to be used. The algebraic framework
shall be revisited by explicating the central point performed by the Fierz
aggregate. Then the spinor classification is generalized in order to encompass
the new mass dimension one spinors. The spinor operator is shown to play a
prominent role to engender the new mass dimension one spinors, accordingly.Comment: 7 pages, final version to appear in Eur. Phys. J.
On the bilinear covariants associated to mass dimension one spinors
In this paper we approach the issue of Clifford algebra basis deformation,
allowing for bilinear covariants associated to Elko spinors which satisfy the
Fierz-Pauli-Kofink identities. We present a complete analysis of covariance,
taking into account the involved dual structure associated to Elko. Moreover,
the possible generalizations to the recently presented new dual structure are
performed.Comment: 9 pages, 0 figure
On the Spinor Representation
A systematic study of the spinor representation by means of the fermionic
physical space is accomplished and implemented. The spinor representation space
is shown to be constrained by the Fierz-Pauli-Kofink identities among the
spinor bilinear covariants. A robust geometric and topological structure can be
manifested from the spinor space, wherein, for instance, the first and second
homotopy groups play prominent roles on the underlying physical properties,
associated to the fermionic fields.Comment: 16 page
Phase-transitions in spin-crossover thin films probed by graphene transport measurements
Future multi-functional hybrid devices might combine switchable molecules and
2D material-based devices. Spin-crossover compounds are of particular interest
in this context since they exhibit bistability and memory effects at room
temperature while responding to numerous external stimuli. Atomically-thin 2D
materials such as graphene attract a lot of attention for their fascinating
electrical, optical, and mechanical properties, but also for their reliability
for room-temperature operations. Here, we demonstrate that thermally-induced
spin-state switching of spin-crossover nanoparticle thin films can be monitored
through the electrical transport properties of graphene lying underneath the
films. Model calculations indicate that the charge carrier scattering mechanism
in graphene is sensitive to the spin-state dependence of the relative
dielectric constants of the spin-crossover nanoparticles. This graphene sensor
approach can be applied to a wide class of (molecular) systems with tunable
electronic polarizabilities.Comment: main text: 13 pages, 5 figures ; SI: 14 pages, 12 figure
Diffusion of charged particles in tokamak‐like stochastic magnetic and electric fields
In this paper the diffusion of guiding centers induced by stochastic magnetic and electric field fluctuations, with both time and space dependence, is analyzed for the case of tokamak plasmas. General experimental results on tokamak fluctuations are used to derive guiding‐center equations that properly describe the particle motion. These equations assume uniform average magnetic and electric fields with random stationary Gaussian fluctuations that constitute a homogeneous and cylindrically symmetric turbulence. By applying Novikov’s theorem, a Fokker–Planck equation for the probability distribution function is derived and an expression for the guiding‐center diffusion coefficient is obtained. This coefficient not only contains the standard terms due to the stochastic wandering of the magnetic lines and the stochastic electric drift, but also new terms due to the stochastic curvature and ∇B drifts. The form of these terms is shown explicitly in terms of the correlation functions of the fields.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70770/2/PFBPEI-4-12-3935-1.pd
Weak ferromagnetism with very large canting in a chiral lattice: (pyrimidine)2FeCl2
The transition metal coordination compound (pyrimidine)2FeCl2 crystallizes in
a chiral lattice, space group I 4_1 2 2 (or I4_3 2 2). Combined magnetization,
Mossbauer spectroscopy and powder neutron diffraction studies reveal that it is
a canted antiferromagnet below T_N = 6.4 K with an unusually large canting of
the magnetic moments of 14 deg. from their general antiferromagnetic alignment,
one of the largest reported to date. This results in weak ferromagnetism with a
ferromagnetic component of 1 mu_B. The large canting is due to the interplay
between the antiferromagnetic exchange interaction and the local single-ion
anisotropy in the chiral lattice. The magnetically ordered structure of
(pyrimidine)2FeCl2, however, is not chiral. The implications of these findings
for the search of molecule based materials exhibiting chiral magnetic ordering
is discussed.Comment: 6 pages, 5 figure
Scanning tunneling spectroscopy of layers of superconducting 2H-TaSe: Evidence for a zero bias anomaly in single layers
We report a characterization of surfaces of the dichalcogenide TaSe using
scanning tunneling microscopy and spectroscopy (STM/S) at 150 mK. When the top
layer has the 2H structure and the layer immediately below the 1T structure, we
find a singular spatial dependence of the tunneling conductance below 1 K,
changing from a zero bias peak on top of Se atoms to a gap in between Se atoms.
The zero bias peak is additionally modulated by the commensurate charge density wave of 2H-TaSe. Multilayers of 2H-TaSe show a
spatially homogeneous superconducting gap with a critical temperature also of 1
K. We discuss possible origins for the peculiar tunneling conductance in single
layers.Comment: 10 pages, 10 figure
- …