174,908 research outputs found
Topological Weyl and Node-Line Semimetals in Ferromagnetic Vanadium-Phosphorous-Oxide -VOPO Compound
We propose that the topological semimetal features can co-exist with
ferromagnetic ground state in vanadium-phosphorous-oxide -VOPO
compound from first-principles calculations. In this magnetic system with
inversion symmetry, the direction of magnetization is able to manipulate the
symmetric protected band structures from a node-line type to a Weyl one in the
presence of spin-orbital-coupling. The node-line semimetal phase is protected
by the mirror symmetry with the reflection-invariant plane perpendicular to
magnetic order. Within mirror symmetry breaking due to the magnetization along
other directions, the gapless node-line loop will degenerate to only one pair
of Weyl points protected by the rotational symmetry along the magnetic axis,
which are largely separated in momentum space. Such Weyl semimetal phase
provides a nice candidate with the minimum number of Weyl points in a condensed
matter system. The results of surface band calculations confirm the non-trivial
topology of this proposed compound. This findings provide a realistic candidate
for the investigation of topological semimetals with time-reversal symmetry
breaking, particularly towards the realization of quantum anomalous Hall effect
in Weyl semimetals.Comment: 5 pages, 4 figure
A family of multiple harmonic sum and multiple zeta star value identities
In this paper we present a new family of identities for multiple harmonic sums which generalize a recent result of Hessami Pilehrood et al [Trans. Amer. Math. Soc. (to appear)]. We then apply it to obtain a family of identities relating multiple zeta star values to alternating Euler sums. In such a typical identity the entries of the multiple zeta star values consist of blocks of arbitrarily long 2-strings separated by positive integers greater than two while the largest depth of the alternating Euler sums depends only on the number of 2-string blocks but not on their lengths
Exploring the rationale of enlightened shareholder value in the realm of UK company law – the path dependence perspective
Despite conventional beliefs in the predominance of shareholder value, a broader agenda of stakeholder consideration has been advocated in the UK by the recently-introduced ESV principle – the overriding corporate objective in the new company law regime. In this paper, the efficiency of this principle in terms of stakeholder enhancement is challenged through an interdisciplinary analysis. Through a critical review of the ESV principle, it is discovered that stakeholder enhancement practices in the context of the 2006 company law regime are still for the fundamental goal of shareholder value maximisation, and that their enlightened impact has been fairly limited in practice. Furthermore, by revisiting the interrelationships between UK economic, political and cultural factors with the predominance objective of shareholder value maximisation in the Companies Act 2006, it is discovered that the enlightened effect of this new approach in the company law regime is in fact impeded by strong, persistent forces deriving from shareholder-oriented particulars. Providing insight into the future direction of corporate governance practice, the paper concludes the rationale behind the shareholder-oriented ESV principle, and further suggests the continuing predominance of shareholder value in UK corporate governance
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