We construct a microscopic theory for the proton spin-lattice relaxation-rate 1/T1 measurements around field-induced level crossings in a single crystal of the trivalent chromium ion wheel complex ...Cr8F8(OOCtBu)16 at sufficiently low temperatures E. Micotti et al., Phys. Rev. B 72 (2005) 020405(R). Exactly diagonalizing a well-equipped spin Hamiltonian for the individual clusters and giving further consideration to their possible interactions, we reveal the mechanism of 1/T1 being single-peaked normally at the first level crossing but double-peaked intriguingly around the second level crossing. We wipe out the doubt about poor crystallization and find out a solution—intramolecular alternating Dzyaloshinsky–Moriya interaction combined with intermolecular coupling of antiferromagnetic character, each of which is so weak as several tens of mK in magnitude.
Abstract
We demonstrate configuration-interaction and Green’s function approaches to the Shastry-Shraiman fourth-order magnetic Raman response of Heisenberg antiferromagnets on the two-dimensional C
...5v
Penrose and C
8v
Ammann-Beenker lattices. Beyond the Loudon-Fleury second-order perturbation scheme, two more symmetry species A
1
and A
2
become Raman-active to break the depolarized Loudon-Fleury Raman response of E
2
symmetry. The A
1
and A
2
modes are activated by dynamic ring exchange and chiral spin fluctuations, respectively, the former of which owes much to multimagnon scatterings in a complicated manner, while the latter of which owes much to aperiodic arrangements of different rhombuses.
A spin‐wave analysis of magnetic Raman scattering in an antiferromagnetic Heisenberg model on the 2D Penrose lattice of C5v point symmetry is made. Following the Shastry–Shraiman perturbation scheme ...for a strongly correlated Hubbard model, fourth‐order effective Raman operators are obtained. Within the second‐order mechanism, there is one and only Raman active mode of E2 symmetry, yielding a spectral weight independent of light polarization. Considering the fourth‐order scatterings as well, activates A1 and A2 as well as E2 modes and therefore results in polarization‐dependent Raman spectra. With the use of linearly and circularly polarized lights, all the symmetry species can separately be extracted from observations. Though the linear spin‐wave theory, i.e., the harmonic oscillator approximation, is far from quantitative, the A2 and E2 Raman intensities are well describable with two magnon interactions. The Raman‐active A1 mode owes much to higher‐order magnon–magnon interactions as well.
Theoretical calculations of the magnetic Raman scattering on the 2D quasiperiodic Heisenberg antiferromagnets are reported. The Raman scattering intensity profile detects various magnetic excitations, including spin‐chirality fluctuations. The interactions between magnons play an important role in the magnetic Raman scattering process.
The purpose of this study is to propose new conditions with which to classify consumers who choose new modes of consumption other than ownership that influence the growth of the sharing economy in ...Japan. Our findings highlight the characteristics of consumers who choose the new consumption mode from a consumer behavior perspective, which is different from previous studies that have focused on ownership to date. By analyzing the results of a qualitative survey of car sharing services (CSS) users through group interviews, hypotheses were formulated regarding the dimensions that classify the characteristics of consumers who choose to use CSS, and these hypotheses were verified by analyzing the results of a quantitative survey. CSS is considered a substitute for the private car and is expected to contribute to the effective use of resources, but it is used as a complement to the private car and to realize a commitment to the car. The method proposed in this study to categorize and understand the factors that influence consumers’ decisions to choose new modes of consumption other than ownership may have implications for marketing strategies, allowing them to respond to the growth of the sharing economy in other countries as well. This will support sustainability and the various experiences of consumption.
A novel determination method for protein biomarkers based on on-chip flow rate measurement was developed using a microchip with organic photodiodes (OPDs). This quantitative method is based on the ...flow rate measurement of an ink solution pushed out by oxygen gas generated through catalase reaction. The amount of oxygen gas generated in the sample reservoir is dependent on the concentration of the analyte; therefore, the flow rate of the ink solution is also dependent on the concentration of the analyte. The concentration of the analyte can thus be estimated by measurement of the ink solution flow rate. The ink solution flow rate was estimated by measuring the migration time of the ink solution between two points using two OPDs placed below the microchannel. The principle of this method was demonstrated by the measurement of catalase using the microchip. In addition, the developed method was applied to the determination of C-reactive protein (CRP), a biomarker of inflammation, based on a catalase-linked immunosorbent assay (C-LISA). The limit of detection for CRP was 0.20 µg/mL. The method was also applied to the determination of CRP in human serum, and the quantitative values obtained by this method were in excellent agreement with those obtained by the conventional enzyme-linked immunosorbent assay (ELISA) method. The developed method does not require a photodetector with high sensitivity and is thus capable of downsizing; therefore, this will be useful for on-site analyses such as point-of-care testing and field measurements.
Graphical Abstract
Abstract
We propose a new scheme of modifying spin waves so as to describe the thermodynamic properties of various noncollinear antiferromagnets with particular interest in a comparison between edge- ...versus corner-sharing triangular-based lattices. The well-known modified spin-wave theory for collinear antiferromagnets diagonalizes a bosonic Hamiltonian subject to the constraint that the total staggered magnetization be zero. Applying this scheme to frustrated noncollinear antiferromagnets ends in a poor thermodynamics, missing the optimal ground state and breaking the local U(1) rotational symmetry. We find such a plausible double-constraint condition for spin spirals as to spontaneously go back to the traditional single-constraint condition at the onset of a collinear Néel-ordered classical ground state. We first diagonalize only the bilinear terms in Holstein-Primakoff boson operators on the order of spin magnitude
S
and then bring these linear spin waves into interaction in a perturbative rather than variational manner. We demonstrate specific-heat calculations in terms of thus-modified interacting spin waves on various triangular-based lattices. In zero dimension, modified-spin-wave findings in comparison with finite-temperature Lanczos calculations turn out so successful as to reproduce the monomodal and bimodal specific-heat temperature profiles of the triangular-based edge-sharing Platonic and corner-sharing Archimedean polyhedral-lattice antiferromagnets, respectively. In two dimensions, high-temperature series expansions and tensor-network-based renormalization-group calculations are still controversial especially at low temperatures, and under such circumstances, modified spin waves interestingly predict that the specific heat of the kagome-lattice antiferromagnet in the corner-sharing geometry remains having both mid-temperature broad maximum and low-temperature narrow peak in the thermodynamic limit, while the specific heat of the triangular-lattice antiferromagnet in the edge-sharing geometry retains a low-temperature sharp peak followed by a mid-temperature weak anormaly in the thermodynamic limit. By further calculating one-magnon spectral functions in terms of our newly developed double-constraint modified spin-wave theory, we reveal that not only the elaborate modification scheme but also quantum corrections, especially those caused by the
O
(
S
0
) primary self-energies, are key ingredients in the successful description of triangular-based-lattice noncollinear antiferromagnets over the whole temperature range of absolute zero to infinity.
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