Peierls-type structural phase transition in a crystal induced by magnetic breakdown

We predict a new type of phase transition in a quasi-two dimensional system of electrons at high magnetic fields, namely the stabilization of a density wave which transforms a two dimensional open Fermi surface into a periodic chain of large pockets with small distances between them. The quantum tunneling of electrons between the neighboring closed orbits enveloping these pockets transforms the electron spectrum into a set of extremely narrow energy bands and gaps which decreases the total electron energy, thus leading to a magnetic breakdown induced density wave (MBIDW) ground state. We show that this DW instability has some qualitatively different properties in comparison to analogous DW instabilities of Peierls type. E. g. the critical temperature of the MBIDW phase transition arises and disappears in a peculiar way with a change of the inverse magnetic field

Competing SDW Phases and Quantum Oscillations in (TMTSF)2ClO4 in Magnetic Field

We propose a new approach for studying spin density waves (SDW) in the Bechgaard salt (TMTSF)2ClO4 where lattice is dimerized in transverse direction due to anion ordering. The SDW response is calculated in the matrix formulation that rigorously treats the hybridization of inter-band and intra-band SDW correlations. Since the dimerization gap is large, of the order of transverse bandwidth, we also develop an exact treatment of magnetic breakdown in the external magnetic field. The obtained results agree with the experimental data on the fast magneto-resistance oscillations. Experimentally found 260T rapid oscillations and the characteristic Tc dependance on magnetic field of relaxed material are fitted with our results for anion potential of the order of interchain hopping

Magnetic oscillations and field induced spin density waves in (TMTSF)_2ClO_4

We report an analysis of the effects of magnetic field on a quasi-one-dimensional band of interacting electrons with a transverse dimerizing potential. One-particle problem in bond-antibond representation is solved exactly. The resulting propagator is used to calculate the spin-density-wave (SDW) response of the interacting system within the matrix RPA for the SDW susceptibility. We predict the magnetic field induced transition of the first order between interband SDW_0 and intraband SDW_(+-) phases. We reproduce the rapid oscillations with a period of 260 Tesla and the overal profile of the TMTSF_2ClO_4 phase diagram.Comment: 6 pages, 3 figure

Requisite variety and intercultural teams: to what extent is Ashby's law useful ?

Requisite variety and intercultural teams: To what extent is Ashby's law useful? The “Law of Requisite Variety” (LRV) is frequently evoked to explain the design, functioning and performance of intercultural teams. But to what extent does the law really enhance understanding in this particular field? The authors consider that LRV has rarely been questioned in-depth in management studies. The paper briefly details LRV in the cybernetics context before “translating” it to social systems, organizations and intercultural teams. Using a qualitative case-study method, the case of an intercultural team is analysed and questioned from the perspective of LRV. The results show that LRV superficially fits the composition of this team, but is unable to explain the human and social dynamics that evolve during the work process.law of requisite variety; requisite variety; intercultural teams ; complexity ; diversity; systems; case study

Rating the Relevant Factors of Business Conditions for Entrepreneurs in Serbia

In this paper were processed and analyzed the attitudes and opinions of potential entrepreneurs regarding to starting their own businesses, in order to scan favorable conditions for development of entrepreneurship in Serbia. As a basic research instrument, a questionnaire with questions about the possibilities and limitations of entrepreneurial business was designed, with the task of identification and assessment of relevant factors that condition the operations of entrepreneurs in Serbia. Throughout the conducted research, it was concluded there are numerous obstacles to business start-ups and successful growth and development of entrepreneurship in Serbia. Participants of the survey believe they have competencies for starting their own business, but due to the unfavorable market conditions and the lack of financial resources, do not see themselves as employers. Analyzing of efforts and time, as well as the risks they take, it is concluded that most of them are not motivated to engage in entrepreneurship and does not plan a professional career in that field