Frustration Driven Stripe Domain Formation in Co/Pt Multilayer Films

We report microscopic mechanisms for an unusual magnetization reversal behavior in Co/Pt multilayers where some of the first-order reversal curves protrude outside of the major loop. Transmission x-ray microscopy reveals a fragmented stripe domain topography when the magnetic field is reversed prior to saturation, in contrast to an interconnected pattern when reversing from a saturated state. The different domain nucleation and propagation behaviors are due to unannihilated domains from the prior field sweep. These residual domains contribute to random dipole fields that impede the subsequent domain growth and prevent domains from growing as closely together as for the interconnected pattern.Comment: 13 pages, 3 figures, to appear in AP

Carving Out Legacy Assets: A Successful Tool for Bank Restructuring?

Beginning with the proposal by Enria (2017), the paper discusses the scope for successful bank restructuring through a carveout of impaired assets and a transfer of these assets to a government-sponsored asset management company. The paper argues that the success of such an operation requires a use of public funds, either outright or through contingent commitments. Clawback provisions are problematic because they create contingent liabilities that merely shift risks from the assets side to the liabilities sides of banks’ balance sheets. The paper distinguishes between asset impairments coming from considerations of prospective returns and asset impairments coming from frictions in the markets in which these assets are traded. It also distinguishes between threats to bank solvency and threats to bank funding/liquidity. In each case, the success of bank restructuring from asset carveouts depends on the extent to which threats to the bank’s solvency is eliminated. If these threats concern bank funding and asset liquidations at depressed prices, public funds may eventually not be needed. If threats to bank solvency come from nonperforming loans, taxpayer support may be essential. The notion of “real economic value” as the price at which assets should be transferred is problematic and leaves ample room for hidden subsidies. The success of restructuring of the individual bank may itself come at a risk to financial stability as the preservation of existing capacities maintains competitive pressure and depresses bank profitability. Additional risks may come from the burden on the government’s fiscal stance

'Total Assets' Versus 'Risk Weighted Assets': Does it Matter for MREL Requirements?

The paper discusses the role of risk weighting in the determination of minimum requirements for eligible bail-in-able liabilities of banks (MREL), i.e. liabilities that are not exempt from the bail-in tool in bank resolution and that can be written down or converted into equity if losses on assets exceed the available equity and such bailing-in is required to re-establish bank solvency so as to provide a basis for maintaining systemically important operations in resolution. The paper begins with a general discussion of the reasons for introducing bank resolution as a special procedure outside of insolvency law, of the reasons for having the bail-in tool and of the frictions that may stand in the way of successful and frictionless resolution. This discussion emphasizes the importance of having sufficient bail-in-able liabilities available; in contrast, for large institutions that have access to bond markets, the social costs of such requirements are small (unlike the private costs to the banks themselves). However, neither risk weighted nor total assets provide proper guidance for determining MREL. Risk-weighting suffers from a lack of a proper statistical basis and a certain manipulability. Moreover, the risk weighting that is used for capital regulation is not well suited for determining MREL; whereas capital regulation focuses on the probability of bad results, MREL is concerned with the extent of losses conditional on results being bad. “Total assets” suffer from not truly representing total assets because various rules, e.g. for netting, allow banks to keep certain assets and liabilities off their balance sheets

Poda e desbaste no cultivo de nogueira-pecã em plantios adensados.

Dissertação (Mestre em Ciências) - Programa de Pós-Graduação em Agronomia da Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas, Pelotas. Orientador: Carlos Roberto Martins (CPACT); Coorientador: Marcelo Barbosa Malgarim

Using Muonic Hydrogen in Optical Spectroscopy Experiment to Detect Extra Dimensions

Considering that gravitational force might deviate from Newton's inverse-square law (ISL) and become much stronger in small scale, we propose a kind of optical spectroscopy experiment to detect this possible deviation and take electronic, muonic and tauonic hydrogen atoms as examples. This experiment might be used to indirectly detect the deviation of ISL down to nanometer scale and to explore the possibility of three extra dimensions in ADD's model, while current direct gravity tests cannot break through micron scale and go beyond two extra dimensions scenario.Comment: 9 pages, 2 figures. To appear in IJT

Debt overhang and capital regulation

We analyze shareholders' incentives to change the leverage of a firm that has already borrowed substantially. As a result of debt overhang, shareholders have incentives to resist reductions in leverage that make the remaining debt safer. This resistance is present even without any government subsidies of debt, but it is exacerbated by such subsidies. Our analysis is relevant to the debate on bank capital regulation, and complements Admati et al. (2010). In that paper we argued that subsidies that favor debt over equity are the key reason that banks funding costs would be lower if they economize on equity. Subsidies come from public funds, and reducing them does not represent a social cost. It is thus irrelevant for assessing regulation. Other arguments made to support claims that equity is expensive are flawed. Like reduction in subsidies, the effects of leverage reduction on bank managers or shareholders do not represent a social cost. In fact, we show that debt overhang creates inefficiency, since shareholders would resist recapitalization even when this would increase the combined value of the firm to shareholders and creditors. Moreover, debt overhang creates an addiction to leverage through a ratchet effect. In the presence of government guarantees, the inefficiencies of excessive leverage are not fully reflected in banks' borrowing costs. Since banks' high leverage is a source of systemic risks and imposes costs on the public, resistance to leverage reduction leads to social inefficiencies. The main beneficiaries from high leverage may be bank managers. The majority of the banks' shareholders, who hold diversified portfolios and who are part of the public, are likely to be net losers. Our analysis highlights the critical importance of effective capital regulation and high equity requirements, especially for large and systemic financial institutions. We analyze shareholders' preferences when choosing among various ways leverage can be reduced. We show that, with homogeneous assets, if the firm's security and asset trades have zero NPV, and the firm has a single class of debt outstanding, then shareholders find it equally undesirable to deleverage through asset sales, pure recapitalization, or asset expansion with new equity. When these conditions are not met, shareholders can have strong preferences for one approach over another. For example, if the firm can buy back junior debt, asset sales are the preferred way to reduce leverage. This preference for asset sales, or deleveraging can persist even if such sales are inefficient and reduce the total value of the firm

Hysteresis loops of Co-Pt perpendicular magnetic multilayers

We develop a phenomenological model to study magnetic hysteresis in two samples designed as possible perpendicular recording media. A stochastic cellular automata model captures cooperative behavior in the nucleation of magnetic domains. We show how this simple model turns broad hysteresis loops into loops with sharp drops like those observed in these samples, and explains their unusual features. We also present, and experimentally verify, predictions of this model, and suggest how insights from this model may apply more generally.Comment: 4.5 pages, 5 figure

Verbs or Nouns? A cross-linguistic study examining the effect of morphological complexity and input on children's early lexical development

Despite considerable differences in the structures of the world's languages and child-rearing practices, children show remarkable cross-linguistic similarities in their early lexical development, including a preference for nouns. Here, we analyze children's early lexical production in naturalistic longitudinal corpora in a large-scale cross-linguistic comparison of 10 typologically highly diverse languages. We assess morphological complexity as a possible explanatory variable for children's higher noun-to-verb ratios and evaluate whether children's gradual increase in morphological productivity is correlated with their gradual decrease in noun-to-verb ratios towards the level found in their ambient language. We show that in languages with complex verb morphology, children exhibit a higher deviation in their noun-to-verb ratio compared to adults. This deviation gradually diminishes as they become more productive in the use of their target language. This effect holds across languages, despite their differences in morphological complexity

Field-test of a robust, portable, frequency-stable laser

We operate a frequency-stable laser in a non-laboratory environment where the test platform is a passenger vehicle. We measure the acceleration experienced by the laser and actively correct for it to achieve a system acceleration sensitivity of $\Delta f / f$ = $11(2) \times 10^{-12}$/g, $6(2) \times 10^{-12}$/g, and $4(1) \times 10^{-12}$/g for accelerations in three orthogonal directions at 1 Hz. The acceleration spectrum and laser performance are evaluated with the vehicle both stationary and moving. The laser linewidth in the stationary vehicle with engine idling is 1.7(1) Hz

Influence of ion irradiation on switching field and switching field distribution in arrays of Co/Pd-based bit pattern media

International audienceWe have used ion irradiation to tune switching field and switching field distribution ͑SFD͒ in polycrystalline Co/Pd multilayer-based bit pattern media. Light He + ion irradiation strongly decreases perpendicular magnetic anisotropy amplitude due to Co/Pd interface intermixing, while the granular structure, i.e., the crystalline anisotropy, remains unchanged. In dot arrays, the anisotropy reduction leads to a decrease in coercivity ͑H C ͒ but also to a strong broadening of the normalized SFD/ H C ͑in percentage͒, since the relative impact of misaligned grains is enhanced. Our experiment thus confirms the major role of misorientated grains in SFD of nanodevice arrays. Today a major research effort in magnetism is targeted toward achieving ultrahigh density data storage with nano-scale magnets. Spin-transfer magnetic random access memory ͑spin-RAM͒ and bit patterned media ͑BPM͒ technologies are currently part of the most promising media. The implementation of both of these technologies relies on achieving in-detail physical understanding and control of the magnetization reversal mechanism in each nanoscopic individual bit to ensure reproducibility of the bit properties in order to avoid write errors. Perpendicular magnetic anisotropy ͑PMA͒ materials, such as polycrystalline Co/Pd, Co/Pt, and Co/Ni multilayers, are believed to be promising materials for both spin-RAM and BPM applications. 1–4 Indeed, they have a well defined high amplitude uniaxial anisotropy that provides good thermal stability while offering low critical current in spin-transfer devices 2 and tunable switching fields in BPM.