Downstream Consequences of Post-Transgression Responses: A Motive-Attribution Framework

Victims commonly respond to experienced wrongdoing by punishing or forgiving the transgressor. While much research has looked at predictors and immediate consequences of these post-transgression responses, comparably less research has addressed the conditions under which punishment or forgiveness have positive or negative downstream consequences on the victim–transgressor relationship. Drawing from research on Social Value Orientation (SVO), we argue that both forgiveness and punishment can be rooted in either prosocial (i.e., relationship- or other-oriented), individualistic (i.e., self-oriented), or competitive (i.e., harm-oriented) motives pursued by the victim. Furthermore, we posit that downstream consequences of forgiveness and punishment crucially depend on how the transgressor interprets the victim’s response. The novel motive-attribution framework presented here highlights the importance of alignment between a victim’s motives and a transgressor’s motive attributions underlying post-transgression responses. This framework thus contributes to a better understanding of positive and negative dynamics following post-transgression interactions

One-Center Charge Transfer Transitions in Manganites

In frames of a rather conventional cluster approach, which combines the crystal field and the ligand field models we have considered different charge transfer (CT) states and O 2p-Mn 3d CT transitions in MnO$_{6}^{9-}$ octahedra. The many-electron dipole transition matrix elements were calculated using the Racah algebra for the cubic point group. Simple "local" approximation allowed to calculate the relative intensity for all dipole-allowed $\pi -\pi$ and $\sigma -\sigma$ CT transitions. We present a self-consistent description of the CT bands in insulating stoichiometric LaMn$^{3+}$O$_3$ compound with the only Mn$^{3+}$ valent state and idealized octahedral MnO$_{6}^{9-}$ centers which allows to substantially correct the current interpretation of the optical spectra. Our analysis shows the multi-band structure of the CT optical response with the weak low-energy edge at 1.7 eV, associated with forbidden $t_{1g}(\pi)-e_{g}$ transition and a series of the weak and strong dipole-allowed high-energy transitions starting from 2.5 and 4.5 eV, respectively, and extending up to nearly 11 eV. The most intensive features are associated with two strong composite bands near $4.6\div 4.7$ eV and $8\div 9$ eV, respectively, resulting from the superposition of the dipole-allowed $\sigma -\sigma$ and $\pi -\pi$ CT transitions. These predictions are in good agreement with experimental spectra. The experimental data point to a strong overscreening of the crystal field parameter $Dq$ in the CT states of MnO$_{6}^{9-}$ centers.Comment: 10 pages, 3 figure

Static and Dynamical Properties of the Ferromagnetic Kondo Model with Direct Antiferromagnetic Coupling Between the localized t2gt_{2g} Electrons

The phase diagram of the Kondo lattice Hamiltonian with ferromagnetic Hund's coupling in the limit where the spin of the localized $t_{2g}$ electrons is classical is analyzed in one dimension as a function of temperature, electronic density, and a direct antiferromagnetic coupling $J'$ between the localized spins. Studying static and dynamical properties, a behavior that qualitatively resembles experimental results for manganites occurs for $J'$ smaller than 0.11 in units of the $e_g$ hopping amplitude. In particular a coexistence of ferromagnetic and antiferromagnetic excitations is observed at low-hole density in agreement with neutron scattering experiments on $\rm{La_{2-2x}Sr_{1+2x}Mn_2O_7}$ with$x=0.4$. This effect is caused by the recently reported tendency to phase separation between hole-rich ferromagnetic and hole-undoped antiferromagnetic domains in electronic models for manganites. As $J'$ increases metal-insulator transitions are detected by monitoring the optical conductivity and the density of states. The magnetic correlations reveal the existence of spiral phases without long-range order but with fairly large correlation lengths. Indications of charge ordering effects appear in the analysis of charge correlations.Comment: 14 pages with 25 eps figures embeded in the tex

Orbital dynamics: The origin of the anomalous optical spectra in ferromagnetic manganites

We discuss the role of orbital degeneracy in the transport properties of perovskite manganites, focusing in particular on the optical conductivity in the metallic ferromagnetic phase at low temperatures. Orbital degeneracy and strong correlations are described by an orbital t-J model which we treat in a slave-boson approach. Employing the memory-function formalism we calculate the optical conductivity, which is found to exhibit a broad incoherent component extending up to bare bandwidth accompanied by a strong suppression of the Drude weight. Further, we calculate the constant of T-linear specific heat. Our results are in overall agreement with experiment and suggest low-energy orbital fluctuations as the origin of the strongly correlated nature of the metallic phase of manganites.Comment: To appear in: Phys. Rev. B 58 (Rapid Communications), 1 November 199

Charge and orbital order in half-doped manganites

An explanation is given for the charge order, orbital order and insulating state observed in half-doped manganese oxides, such as Nd$_{1/2}$Sr$_{1/2}$MnO$_{3}$. The competition between the kinetic energy of the electrons and the magnetic exchange energy drives the formation of effectively one-dimensional ferromagnetic zig-zag chains. Due to a topological phase factor in the hopping, the chains are intrinsically insulating and orbital-ordered. Most surprisingly, the strong Coulomb interaction between electrons on the same Mn-ion leads to the experimentally observed charge ordering. For doping less than 1/2 the system is unstable towards phase separation into a ferromagnetic metallic and charge-ordered insulating phase.Comment: To appear in Phys. Rev. Lett., 4 pages, 4 figure

Thermoelectric Response Near the Density Driven Mott Transition

We investigate the thermoelectric response of correlated electron systems near the density driven Mott transition using the dynamical mean field theory.Comment: 4 pages, 2 embedded figure

Incoherent Charge Dynamics in Perovskite Manganese Oxides

A minimal model is proposed for the perovskite manganese oxides showing the strongly incoherent charge dynamics with a suppressed Drude weight in the ferromagnetic and metallic phase near the insulator. We investigate a generalized double-exchange model including three elements; the orbital degeneracy of $e_g$ conduction bands, the Coulomb interaction and fluctuating Jahn-Teller distortions. We demonstrate that Lancz$\ddot{\rm o}$s diagonalization calculations combined with Monte Carlo sampling of the largely fluctuating lattice distortions result in the optical conductivity which quantitatively accounts for the experimental indications. It is found that all the three elements are indispensable to understand the charge dynamics in these compounds.Comment: 4 pages with 1 page of figures. To appear in J. Phys. Soc. Jp

Cooperative Jahn-Teller Effect and Electron-Phonon Coupling in La1−xAxMnO3La_{1-x}A_xMnO_3

A classical model for the lattice distortions of \lax is derived and, in a mean field approximation, solved. The model is based on previous work by Kanamori and involves localized Mn d-electrons (which induce tetragonal distortions of the oxygen octahedra surrounding the Mn) and localized holes (which induce breathing distortions). Parameters are determined by fitting to the room temperature structure of $LaMnO_3$. The energy gained by formation of a local lattice distortion is found to be large, most likely $\approx 0.6$ eV per site, implying a strong electorn-phonon coupling and supporting polaronic models of transport in the doped materials. The structural transition is shown to be of the order-disorder type; the rapid x-dependence of the transition temperature is argued to occur because added holes produce a "random" field which misaligns the nearby sites.Comment: 24 pages. No figures. One Table. Late

Polaron Absorption in a Perovskite Manganite La0.7Ca0.3MnO3

Temperature dependent optical conductivity spectra of a La0.7Ca0.3MnO3 (LCMO) sample were measured. In the metallic regime at very low temperatures, they clearly showed two types of absorption features, i.e., a sharp Drude peak and a broad mid-infrared absorption band, which could be explained as coherent and incoherent bands of a large lattice polaron. This elementary excitation in LCMO was found to be in a strong coupling regime and to have interactions with the spin degree of freedom.Comment: 4 pages and separate 4 figure

Microwave properties of Nd_0.5Sr_0.5MnO_3: a key role of the (x^2-y^2)-orbital effects

Transmittance of the colossal magnetoresistive compound Nd_0.5Sr_0.5MnO_3 showing metal-insulator phase transition has been studied by means of the submm- and mm-wavelength band spectroscopy. An unusually high transparency of the material provided direct evidence for the significant suppression of the coherent Drude weight in the ferromagnetic metallic state. Melting of the A-type antiferromagnetic states has been found to be responsible for a considerable increase in the microwave transmission, which was observed at the transition from the insulating to the metallic phase induced by magnetic field or temperature. This investigation confirmed a dominant role of the (x^2-y^2)-orbital degree of freedom in the low-energy optical properties of Nd_0.5Sr_0.5MnO_3 and other doped manganites with planar (x^2-y^2)-orbital order, as predicted theoretically. The results are discussed in terms of the orbital-liquid concept.Comment: 8 pages, 3 figure