1,004 research outputs found
Field-induced magnetic behavior in quasi-one-dimensional Ising-like antiferromagnet BaCo2V2O8: A single-crystal neutron diffraction study
BaCo2V2O8 is a nice example of a quasi-one-dimensional quantum spin system
that can be described in terms of Tomonaga-Luttinger liquid physics. This is
explored in the present study where the magnetic field-temperature phase
diagram is thoroughly established up to 12 T using single-crystal neutron
diffraction. The transition from the N\'eel phase to the incommensurate
longitudinal spin density wave (LSDW) phase through a first-order transition,
as well as the critical exponents associated with the paramagnetic to ordered
phase transitions, and the magnetic order both in the N\'eel and in the LSDW
phase are determined, thus providing a stringent test for the theory.Comment: 17 pages with 15 figure
Neutron diffraction investigation of the H-T phase diagram above the longitudinal incommensurate phase of BaCo2V2O8
The quasi-one-dimensional antiferromagnetic Ising-like compound BaCo2V2O8 has
been shown to be describable by the Tomonaga-Luttinger liquid theory in its
gapless phase induced by a magnetic field applied along the Ising axis. Above
3.9 T, this leads to an exotic field-induced low-temperature magnetic order,
made of a longitudinal incommensurate spin-density wave, stabilized by weak
interchain interactions. By single-crystal neutron diffraction we explore the
destabilization of this phase at a higher magnetic field. We evidence a
transition at around 8.5 T towards a more conventional magnetic structure with
antiferromagnetic components in the plane perpendicular to the magnetic field.
The phase diagram boundaries and the nature of this second field-induced phase
are discussed with respect to previous results obtained by means of nuclear
magnetic resonance and electron spin resonance, and in the framework of the
simple model based on the Tomonaga-Luttinger liquid theory, which obviously has
to be refined in this complex system.Comment: 7 pages, 5 figure
Applicant Faking on Personality Tests: Good or Bad and Why Should We Care?
The unitarian understanding of construct validity holds that deliberate response distortion in completing self-report personality tests (i.e., faking) threatens trait-based inferences drawn from test scores. This “faking-is-bad” (FIB) perspective is being challenged by an emerging “faking-is-good” (FIG) position that condones or favors faking and its underlying attributes (e.g., social skill, ATIC) to the degree they contribute to predictor–criterion correlations and are job relevant. Based on the unitarian model of validity and relevant empirical evidence, we argue the FIG perspective is psychometrically flawed and counterproductive to personality-based selection targeting trait-based fit. Carrying forward both positions leads to variously dark futures for self-report personality tests as selection tools. Projections under FIG, we suggest, are particularly serious. FIB offers a more optimistic future but only to the degree faking can be mitigated. Evidence suggesting increasing applicant faking rates and other alarming trends makes the FIB versus FIG debate a timely if not urgent matter
Single domain magnetic helicity and triangular chirality in structurally enantiopure Ba3NbFe3Si2O14
A novel doubly chiral magnetic order is found out in the structurally chiral
langasite compound BaNbFeSiO. The magnetic moments are
distributed over planar frustrated triangular lattices of triangle units. On
each of these they form the same triangular configuration. This ferro-chiral
arrangement is helically modulated from plane to plane. Unpolarized neutron
scattering on a single crystal associated with spherical neutron polarimetry
proved that a single triangular chirality together with a single helicity is
stabilized in an enantiopure crystal. A mean field analysis allows discerning
the relevance on this selection of a twist in the plane to plane
supersuperexchange paths
Longitudinal and Transverse Zeeman Ladders in the Ising-Like Chain Antiferromagnet BaCo2V2O8
We explore the spin dynamics emerging from the N\'eel phase of the chain
compound antiferromagnet BaCo2V2O8. Our inelastic neutron scattering study
reveals unconventional discrete spin excitations, so called Zeeman ladders,
understood in terms of spinon confinement, due to the interchain attractive
linear potential. These excitations consist in two interlaced series of modes,
respectively with transverse and longitudinal polarization. The latter have no
classical counterpart and are related to the zero-point fluctuations that
weaken the ordered moment in weakly coupled quantum chains. Our analysis
reveals that BaCo2V2O8, with moderate Ising anisotropy and sizable interchain
interactions, remarkably fulfills the conditions necessary for the observation
of these longitudinal excitations.Comment: 5 pages, 4 figures, 2 additional pages of supplemental material with
2 figures; Journal ref. added; 1 page erratum added at the end with 1 figur
Tunable gauge potential for neutral and spinless particles in driven lattices
We present a universal method to create a tunable, artificial vector gauge
potential for neutral particles trapped in an optical lattice. The necessary
Peierls phase of the hopping parameters between neighboring lattice sites is
generated by applying a suitable periodic inertial force such that the method
does not rely on any internal structure of the particles. We experimentally
demonstrate the realization of such artificial potentials, which generate
ground state superfluids at arbitrary non-zero quasi-momentum. We furthermore
investigate possible implementations of this scheme to create tuneable magnetic
fluxes, going towards model systems for strong-field physics
Experimental study of the competition between Kondo and RKKY interactions for Mn spins in a model alloy system
The quasicrystal Al-Pd-Mn is a model system for an experimental study of the
competition between Ruderman-Kittel-Kasuya-Yoshida (RKKY) and Kondo
interactions. First, specific of such alloys, only a few Mn atoms carry an
effective spin and their concentration x is tunable over several orders of
magnitude, even though the Mn amount is almost constant. Second, the
characteristic energy scales for the interactions lie in the Kelvin range.
Hence we could study the magnetization on both side of these energy scales,
covering a range of temperatures [0.1-100 K] and magnetic fields (mu_B H/k_B= 0
to 5 K) for 22 samples and x varying over 2 decades. Using very general Kondo
physics arguments, and thus carrying out the data analysis with no preconceived
model, we found a very robust and simple result: The magnetization is a sum of
a pure Kondo (T_K=3.35K) and a pure RKKY contributions, whatever the moment
concentration is and this surprisingly up to the concentration where the RKKY
couplings dominate fully and thus cannot be considered as a perturbation.Comment: 18 pages, 18 figure
Faking Is as Faking Does: A Rejoinder to Marcus (2021)
Applicant faking poses serious threats to achieving personality-based fit, negatively affecting both the worker and the organization. In articulating this “faking-is-bad” (FIB) position, Tett and Simonet (2021) identify Marcus’ (2009) self-presentation theory (SPT) as representative of the contrarian “faking-is-good” camp by its advancement of self-presentation as beneficial in hiring contexts. In this rejoinder, we address 20 of Marcus’ (2021) claims in highlighting his reliance on an outdated empiricist rendering of validity, loosely justified rejection of the negative and moralistic “faking” label, disregard for the many challenges posed by blatant forms of faking, inattention to faking research supporting the FIB position, indefensibly ambiguous constructs, and deep misunderstanding of person–workplace fit based on personality assessment. In demonstrating these and other limitations of Marcus’ critique, we firmly uphold the FIB position and clarify SPT as headed in the wrong direction
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