9,270 research outputs found
Photovoltage Detection of Edge Magnetoplasmon Oscillations and Giant Magnetoplasmon Resonances in A Two-Dimensional Hole System
In our high mobility p-type AlGaAs/GaAs two-dimensional hole samples, we
originally observe the B-periodic oscillation induced by microwave (MW) in
photovoltage (PV) measurements. In the frequency range of our measurements (5 -
40 GHz), the period ({\Delta}B) is inversely proportional to the microwave
frequency (f). The distinct oscillations come from the edge magnetoplasmon
(EMP) in the high quality heavy hole system. In our hole sample with a very
large effective mass, the observation of the EMP oscillations is in neither the
low frequency limit nor the high frequency limit, and the damping of the EMP
oscillations is very weak under high magnetic fields. Simultaneously, we
observe the giant plasmon resonance signals in our measurements on the shallow
two-dimensional hole system (2DHS)
Thermopower and Nernst measurements in a half-filled lowest Landau level
Motivated by recent proposal by Potter et al. [Phys. Rev. X 6, 031026 (2016)]
concerning possible thermoelectric signatures of Dirac composite fermions, we
perform a systematic experimental study of thermoelectric transport of an
ultrahigh-mobility GaAs/AlxGa1-xAs two dimensional electron system at filling
factor v = 1/2. We demonstrate that the thermopower Sxx and Nernst Sxy are
symmetric and anti-symmetric with respect to B = 0 T, respectively. The
measured properties of thermopower Sxx at v = 1/2 are consistent with previous
experimental results. The Nernst signals Sxy of v = 1/2, which have not been
reported previously, are non-zero and show a power law relation with
temperature in the phonon-drag dominant region. In the electron-diffusion
dominant region, the Nernst signals Sxy of v = 1/2 are found to be
significantly smaller than the linear temperature dependent values predicted by
Potter et al., and decreasing with temperature faster than linear dependence.Comment: 23 pages, 5 figure
Unusual Coupling Between Field-induced Spin Fluctuations and Spin Density Wave in Intermetallic CeAg2Ge2
We report on the experimental evidences for an unusual coupling between the
magnetic field- induced fluctuations of correlated Ce-ions coinciding with the
discontinuous movement of the underlying spin density wave in the intermetallic
rare earth compound CeAg2Ge2. The measurements performed using neutron
scattering and magnetic Gruneisen ratio methods suggest that the coupling
onsets at H= 2.7 T, T < 3.8 K and persists to the lowest measurement
temperature T ~ 0.05 K. These measurements suggest a new mechanism behind the
spin fluctuations which can affect the intrinsic properties of the system.Comment: 4 pages, 4 figures, Strongly correlated electrons syste
Models of Social Groups in Blogosphere Based on Information about Comment Addressees and Sentiments
This work concerns the analysis of number, sizes and other characteristics of
groups identified in the blogosphere using a set of models identifying social
relations. These models differ regarding identification of social relations,
influenced by methods of classifying the addressee of the comments (they are
either the post author or the author of a comment on which this comment is
directly addressing) and by a sentiment calculated for comments considering the
statistics of words present and connotation. The state of a selected blog
portal was analyzed in sequential, partly overlapping time intervals. Groups in
each interval were identified using a version of the CPM algorithm, on the
basis of them, stable groups, existing for at least a minimal assumed duration
of time, were identified.Comment: Gliwa B., Ko\'zlak J., Zygmunt A., Models of Social Groups in
Blogosphere Based on Information about Comment Addressees and Sentiments, in
the K. Aberer et al. (Eds.): SocInfo 2012, LNCS 7710, pp. 475-488, Best Paper
Awar
The mitochondrial ribosome from Locusta migratoria
Mitochondrial ribosomes from locust thorax muscles have been identified recently in our labo-ratory by specific labelling of the adhering nascent peptide chains and have been isolated from mito
Evolution of the bulk properties, structure, magnetic order, and superconductivity with Ni doping in CaFe2-xNixAs2
Magnetization, susceptibility, specific heat, resistivity, neutron and x-ray
diffraction have been used to characterize the properties of single crystalline
CaFe2-xNixAs2 as a function of Ni doping for x varying from 0 to 0.1. The
combined first-order structural and magnetic phase transitions occur together
in the undoped system at 172 K, with a small decrease in the area of the a-b
plane along with an abrupt increase in the length of the c-axis in the
orthorhombic phase. With increasing x the ordered moment and transition
temperature decrease, but the transition remains sharp at modest doping while
the area of the a-b plane quickly decreases and then saturates. Warming and
cooling data in the resistivity and neutron diffraction indicate hysteresis of
~2 K. At larger doping the transition is more rounded, and decreases to zero
for x=0.06. The susceptibility is anisotropic for all values of x. Electrical
resistivity for x = 0.053 and 0.06 shows a superconducting transition with an
onset of nearly 15 K which is further corroborated by substantial diamagnetic
susceptibility. For the fully superconducting sample there is no long range
magnetic order and the structure remains tetragonal at all temperature, but
there is an anomalous increase in the area of the a-b plane in going to low T.
Heat capacity data show that the density of states at the Fermi level increases
for x > 0.053 as inferred from the value of Sommerfeld coefficient. The regime
of superconductivity is quite restrictive, with a maximum TC of 15 K and an
upper critical field Hc2=14 T. Superconductivity disappears in the overdoped
region.Comment: 14 pages, 12 figures. Submitted to Phys. Rev.
Robust pinning of magnetic moments in pyrochlore iridates
Pyrochlore iridates A2Ir2O7 (A = rare earth elements, Y or Bi) hold great
promise for realizing novel electronic and magnetic states owing to the
interplay of spin-orbit coupling, electron correlation and geometrical
frustration. A prominent example is the formation of all-in/all-out
(AIAO)antiferromagnetic order in the Ir4+ sublattice that comprises of
corner-sharing tetrahedra. Here we report on an unusual magnetic phenomenon,
namely a cooling-field induced shift of magnetic hysteresis loop along
magnetization axis, and its possible origin in pyrochlore iridates with
non-magnetic Ir defects (e.g. Ir3+). In a simple model, we attribute the
magnetic hysteresis loop to the formation of ferromagnetic droplets in the AIAO
antiferromagnetic background. The weak ferromagnetism originates from canted
antiferromagnetic order of the Ir4+ moments surrounding each non-magnetic Ir
defect. The shift of hysteresis loop can be understood quantitatively based on
an exchange-bias like effect in which the moments at the shell of the FM
droplets are pinned by the AIAO AFM background via mainly the Heisenberg (J)
and Dzyaloshinsky-Moriya (D) interactions. The magnetic pinning is stable and
robust against the sweeping cycle and sweeping field up to 35 T, which is
possibly related to the magnetic octupolar nature of the AIAO order.Comment: 16 pages, 4 figure
UTJECAJ RELIGIOZNOSTI I DUHOVNOSTI NA SVAKODNEVNU PRAKSU SOCIJALNIH RADNIKA
Although social work can trace the roots of its establishment as a profession to religion/spirituality, the relationship between social work and religion/spirituality has deteriorated due to the former’s professionalisation and secularisation. Nevertheless, religious/spiritual values are important for many social work services and for the practice of the profession. It is, hence, worth demarcating the role of religion/spirituality for frontline social workers. In the current qualitative study, repeated interviews were conducted with 11 Chinese social workers from diverse social work settings. It was noted that Eastern and Western religion/spirituality can instil meaning and value in the profession’s nature.Iako se uspostavljanje socijalnog rada kao profesije temelji na religIoznosti/duhovnosti, odnos između socijalnog rada i religioznosti/duhovnosti narušen je zbog profesionalizacije i sekularizacije socijalnog rada. Usprkos tome, religiozne/duhovne vrijednosti važne su za mnoge usluge socijalnog rada i za praksu socijalnog rada kao profesije. Stoga je važno utvrditi ulogu religioznosti/duhovnosti za najizloženije socijalne radnike. U ovom kvalitativnom istraživanju provedeni su ponovljeni razgovori s 11 kineskih socijalnih radnika iz različitih područja socijalnog rada. Uočeno je da istočnjačka i zapadnjačka religioznost/duhovnost mogu unijeti značenje i vrijednost u prirodu profesije
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