Large magnetoresistance in bcc Co/MgO/Co and FeCo/MgO/FeCo tunneling junctions

By use of first-principles electronic structure calculations, we predict that the magnetoresistance of the bcc Co(100)/MgO(100)/bcc Co(100) and FeCo(100)/MgO(100)/FeCo(100) tunneling junctions can be several times larger than the very large magnetoresistance predicted for the Fe(100)/MgO(100)/Fe(100) system. The origin of this large magnetoresistance can be understood using simple physical arguments by considering the electrons at the Fermi energy travelling perpendicular to the interfaces. For the minority spins there is no state with $\Delta_1$ symmetry whereas for the majority spins there is only a $\Delta_1$ state. The $\Delta_1$ state decays much more slowly than the other states within the MgO barrier. In the absence of scattering which breaks the conservation of momentum parallel to the interfaces, the electrons travelling perpendicular to the interfaces undergo total reflection if the moments of the electrodes are anti-parallel. These arguments apply equally well to systems with other well ordered tunnel barriers and for which the most slowly decaying complex energy band in the barrier has $\Delta_1$ symmetry. Examples include systems with (100) layers constructed from Fe, bcc Co, or bcc FeCo electrodes and Ge, GaAs, or ZnSe barriers.Comment: 8 figure files in eps forma

When Federal Immigration Exclusion Meets Subfederal Workplace Inclusion: A Forensic Approach to Legislative History

What happens when a person is simultaneously viewed as an unauthorized immigrant without rights according to a federal regime and as an employee with rights according to a subfederal regime? In the wake of widespread and inconsistent adjudication of this issue, this Article sheds new light on this pressing question. To date, pertinent court battles and scholarship have led to a virtual stalemate and often focus exclusively on normative policy arguments. By contrast, this Article employs an empirically-grounded review of fifteen years of legislative history to analyze this paradox. This review illustrates that the denial of workplace protections to unauthorized workers runs contrary to immigration law purposes. The Article, therefore, provides a fresh perspective on an otherwise intractable debate. In doing so, it also develops a more scientifically grounded forensic approach to legislative history which addresses some of the most salient and passionate critiques of legislative history and revives legislative history as a more reliable interpretive tool in law and policy analyses

Current-induced torques in textured Rashba ferromagnets

In systems with small spin-orbit coupling, current-induced torques on the magnetization require inhomogeneous magnetization textures. For large spin-orbit coupling, such torques exist even without gradients in the magnetization direction. Here, we consider current-induced torques in ferromagnetic metals with both Rashba spin-orbit coupling and inhomogeneous magnetization. We first phenomenologically construct all torques that are allowed by the symmetries of the system, to first order in magnetization-direction gradients and electric field. Second, we use a Boltzmann approach to calculate the spin torques that arise to second order in the spin-orbit coupling. We apply our results to current-driven domain walls and find that the domain-wall mobility is strongly affected by torques that result from the interplay between spin-orbit coupling and inhomogeneity of the magnetization texture.Comment: 9 pages, 3 figure

Anthropometry of love: Height and gender asymmetries in interethnic marriages

This is the post-print version of the final paper published in Economics and Human Biology. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2010 Elsevier B.V.Both in the UK and in the US, we observe puzzling gender asymmetries in the propensity to outmarry: Black men are more likely to have white spouses than Black women, but the opposite is true for Chinese: Chinese men are half less likely to be married to a White person than Chinese women. We argue that differences in height distributions, combined with a simple preference for the husband to be taller than the wife, can help explain these ethnic-specific gender asymmetries. Blacks are taller than Asians, and we argue that this significantly affects their marriage prospects with whites. We provide empirical support for this hypothesis using data from the Millennium Cohort Study. Specifically, we find that ethnic differences in propensity to intermarry with Whites shrink when we control for the proportion of suitable partners with respect to height. © 2010 Elsevier B.V

Ethnic Studies in the Twenty-First Century: A Proposal

If you will consider the dualistic thinking which undergirds Western philosophical tradition, then it comes as a surprise to no one that the periodization of history is based on white male experiences as the sum of western civilization, especially the glorification of war and the celebration of unbridled raw-power. So, too, it is not surprising that Aristotelian logic and Cartesian metaphysics form the godhead for monocultural and unisexual education in U.S. society, which is at the least bisexual and multicultural. For a decade-and-a-half now, ethnic, minority, and women\u27s studies proponents have suggested that their purposes for existence were to challenge and change the status quo. But ethnic and minority studies people, for the most part, became parties to the evils of the academy rather than revolution aries against them during the past fifteen years

Inverted spin polarization of Heusler alloys for new spintronic devices

A new magnetic logic overcomes the major limitations of field programmable gate arrays while having a 50% smaller unit cell than conventional designs utilizing magnetic tunnel junctions with one Heusler alloy electrode. These show positive and negative TMR values at different bias voltages at room temperature which generally adds an additional degree of freedom to all spintronic devices

Social Composition, Social Conflict, and Economic Development

This paper investigates how people subdivided in social groups behave in an economy without property rights. Facing a linear production technology groups follow Markovian strategies for consumption and investment. Additionally, they may spend effort in an appropriation contest. For a symmetric society I show that conflict prevents investment and growth. In a society at peace economic growth may occur. Growth, however, is decreasing in the degree of social fractionalization and smaller than it could be under secure property rights. In an economy populated by social groups of unequal size an asymmetric equilibrium exists. A large majority may behave peacefully although continuously challenged by a predatory minority. In that case the economy either stagnates or grows at a low rate. Growth is decreasing in the size of the predatory minority and its conflict intensity.Africa’s Growth Tragedy, Property Rights, Social Conflict, Fractionalization

Social Composition, Social Conflict, and Economic Development

This paper investigates how social composition affects social conflict and economic development when property rights are unenforceable. Groups follow Markovian strategies for consumption and investment and may also spend effort in an resource appropriation contest. It is shown that conflict prevents investment and growth in a society of symmetric groups. In a society at peace economic growth may occur. Growth, however, is decreasing in the degree of social fractionalization and smaller than it could be under secure property rights. In an economy populated by social groups of unequal size an asymmetric equilibrium exists. A large majority may behave peacefully although continuously challenged by a predatory minority. The rebelridden economy either stagnates or grows at a low rate. Growth is decreasing in the size of the predatory minority and its conflict intensity. A final part extends the analysis towards behavior of non-benevolent social elites.social conflict; social fractionalization; property rights; stagnation; growth