Tuning spin-orbit coupling and superconductivity at the SrTiO3/LaAlO3 interface: a magneto-transport study

The superconducting transition temperature, Tc, of the SrTiO3/LaAlO3 interface was varied by the electric field effect. The anisotropy of the upper critical field and the normal state magneto-transport were studied as a function of gate voltage. The spin-orbit coupling energy is extracted. This tunable energy scale is used to explain the strong gate dependence of the mobility and of the anomalous Hall signal observed. The spin-orbit coupling energy follows Tc for the electric field range under study

The String Tension in Two Dimensional Gauge Theories

We review and elaborate on properties of the string tension in two-dimensional gauge theories. The first model we consider is massive QED in the $m\ll e$ limit. We evaluate the leading string tension both in the fermionic and bosonized descriptions. We discuss the next to leading corrections in $m/e$. The next-to-leading terms in the long distance behavior of the quark-antiquark potential, are evaluated in a certain region of external versus dynamical charges. The finite temperature behavior is also determined. In $QCD_2$ we review the results for the string tension of quarks in cases with dynamical quarks in the fundamental, adjoint, symmetric and antisymmetric representations. The screening nature of $SYM_2$ is re-derived.Comment: 25 pages, Latex. v2: several changes, mainly in section

An effective thermodynamic potential from the instanton with Polyakov-loop contributions

We derive an effective thermodynamic potential (Omega_eff) at finite temperature (T>0) and zero quark-chemical potential (mu_R=0), using the singular-gauge instanton solution and Matsubara formula for N_c=3 and N_f=2 in the chiral limit. The momentum-dependent constituent-quark mass is also obtained as a function of T, employing the Harrington-Shepard caloron solution in the large-N_c limit. In addition, we take into account the imaginary quark chemical potential mu_I = A_4, translated as the traced Polayakov-loop (Phi) as an order parameter for the Z(N_c) symmsetry, characterizing the confinement (intact) and deconfinement (spontaneously broken) phases. As a result, we observe the crossover of the chiral (chi) order parameter sigma^2 and Phi. It also turns out that the critical temperature for the deconfinment phase transition, T^Z_c is lowered by about (5-10)% in comparison to the case with a constant constituent-quark mass. This behavior can be understood by considerable effects from the partial chiral restoration and nontrivial QCD vacuum on Phi. Numerical calculations show that the crossover transitions occur at (T^chi_c,T^Z_c) ~ (216,227) MeV.Comment: 15 pages, 7 figure

Memo to the Obama Administration on the Burma Responsible Investment Reporting Requirements

In September 2013, CCSI sent a memo to President Obama and his Administration in response to the first public reports submitted by U.S. companies in compliance with the Burma Responsible Investment Reporting Requirements. The memo applauded the U.S. Government’s efforts to encourage responsible investment in Burma, noting that robust due diligence is essential to ensuring that international investments contribute to sustainable development. Yet the memo also urged the Obama Administration to take steps to strengthen future reporting. In particular, CCSI urged the Administration to issue clarifying guidance that any U.S. investor submitting a report should (1) provide information on due diligence policies and procedures related to land rights, and (2) provide thorough information in response to each reporting question, regardless of whether its investments are “passive.

Measuring Land Rights for a Sustainable Future

Land rights, both for individuals and for communities, are critical for achieving sustainable development. Security of land tenure and other rights to the land (sometimes held communally rather than individually) can accelerate poverty reduction, strengthen food security, and empower women. Land rights can reduce resource conflicts, as well as encourage the responsible use of natural resources. As the UN member countries begin to implement the new Sustainable Development Goals (SDGs), they should keep land rights in their focus, and measure and protect land rights in order to achieve the SDGs

On the resistivity at low temperatures in electron-doped cuprate superconductors

We measured the magnetoresistance as a function of temperature down to 20mK and magnetic field for a set of underdoped PrCeCuO (x=0.12) thin films with controlled oxygen content. This allows us to access the edge of the superconducting dome on the underdoped side. The sheet resistance increases with increasing oxygen content whereas the superconducting transition temperature is steadily decreasing down to zero. Upon applying various magnetic fields to suppress superconductivity we found that the sheet resistance increases when the temperature is lowered. It saturates at very low temperatures. These results, along with the magnetoresistance, cannot be described in the context of zero temperature two dimensional superconductor-to-insulator transition nor as a simple Kondo effect due to scattering off spins in the copper-oxide planes. We conjecture that due to the proximity to an antiferromagnetic phase magnetic droplets are induced. This results in negative magnetoresistance and in an upturn in the resistivity.Comment: Accepted in Phys. Rev.

Perturbative analysis of wave interactions in nonlinear systems

This work proposes a new way for handling obstacles to asymptotic integrability in perturbed nonlinear PDEs within the method of Normal Forms - NF - for the case of multi-wave solutions. Instead of including the whole obstacle in the NF, only its resonant part is included, and the remainder is assigned to the homological equation. This leaves the NF intergable and its solutons retain the character of the solutions of the unperturbed equation. We exploit the freedom in the expansion to construct canonical obstacles which are confined to te interaction region of the waves. Fo soliton solutions, e.g., in the KdV equation, the interaction region is a finite domain around the origin; the canonical obstacles then do not generate secular terms in the homological equation. When the interaction region is infifnite, or semi-infinite, e.g., in wave-front solutions of the Burgers equation, the obstacles may contain resonant terms. The obstacles generate waves of a new type, which cannot be written as functionals of the solutions of the NF. When an obstacle contributes a resonant term to the NF, this leads to a non-standard update of th wave velocity.Comment: 13 pages, including 6 figure

Pre- and post-selected ensembles and time-symmetry in quantum mechanics

An expression is proposed for the quantum mechanical state of a pre- and post-selected ensemble, which is an ensemble determined by the final as well as the initial state of the quantum systems involved. It is shown that the probabilities calculated from the proposed state agree with previous expressions, for cases where they both apply. The same probabilities are found when they are calculated in the forward- or reverse-time directions. This work was prompted by several problems raised by Shimony recently in relation to the state, and time symmetry, of pre- and post-selected ensembles.Comment: RevTex4, 17 pages, no fig

SL(2,R)SL(2,R) symmetry and quasi-normal modes in the BTZ black hole

With the help of two new intrinsic tensor fields associated with the $SL(2,R)$ quadratic Casimir of Killing fields, we uncover the $SL(2,R)$ symmetry satisfied by the solutions to the equations of motion for various fields in the BTZ black hole in a uniform way by performing tensor and spinor analysis without resorting to any specific coordinate system. Then with the standard algebraic method developed recently, we determine the quasi-normal modes for various fields in the BTZ black hole. As a result, the quasi-normal modes are given by the infinite tower of descendants of the chiral highest weight mode, which is in good agreement with the previous analytic result obtained by exactly solving equations of motion instead.Comment: JHEP style, 1+13 pages, version to appear in JHE

The Business and Human Rights Arbitration Rule Project: Falling Short of its Access to Justice Objectives

The Hague Rules on Business and Human Rights Arbitration, initiated by the Business and Human Rights Arbitration Working Group, aims to create an international private judicial dispute resolution avenue available to parties involved in business and human rights issues, thereby helping to address the significant remedy gap faced by victims of business-related abuses. With the perspective that “international arbitration holds great promise as a method to be used to resolve human rights disputes involving business,” the Drafting Team released, in November 2018, an Elements Paper on Business and Human Rights Arbitration, as well as, in June 2019, Draft Arbitration Rules on Business and Human Rights. Both documents were released for public consultation and comment. A designated Sounding Board, of which CCSI is a member, was also consulted. With respect to the Elements Paper, CCSI submitted comments to the Drafting Team focusing on the following aspects of the Elements Paper: (1) which parties are necessary and sufficient to ensure effective access to justice of victims, including discussion of the desirable roles for both business and states, (2) the appropriate role for both international human rights law (IHRL) as well as other legal norms, and how IHRL should be interpreted and applied in this context, (3) whether model contract clauses are desirable, (4) the critical importance of choosing the appropriate appointing authority, (5) desirable qualifications of BHR arbitrators, including how they should be selected and how challenges to arbitrators should be handled, (6) how principles of transparency and access to information and effective participation should be treated, (7) the desirability of allowing amicus participation as a matter of right, and (8) principles that should govern allocation of costs, as well as a role for financial assistance for claimants and regulation of third-party funding. Following the release of the Draft Rules, CCSI published this Briefing Note and a blog, Saving the Business and Human Rights Arbitration Rule project: Put Human Rights Holders at the Heart,each of which build on our comments on the Elements Paper and elaborate certain serious concerns that CCSI has regarding the ability of the Draft Rules to advance access to justice in cases of injustices caused or perpetuated by business activity. Our comments are based on observed realities regarding both how arbitration has operated in other contexts and how companies have sought generally to avoid liability for human rights harms, as well as the steps that companies would need to take to facilitate arbitration and the enforcement of judgments against them. We suggest, among other things, that pressure devoted to seeing corporates submit to BHR Arbitration also be devoted to stopping them from undermining access to justice in domestic courts. We also note that the Draft Rules suffer from procedural and substantive gaps. As a procedural matter, we urge that, before the Draft Rules are finalized, every single one is reviewed carefully by a specific group that is representative of rights-holders and potential claimants. In terms of substance, multiple points, detailed in the above publications, also give us pause. These include, among others: the lack of anti-retaliation protections; a suggested loser-pays fee-shifting arrangement that ignores the reality of most human rights claimants; vague guidance on early dismissal of claims that could further tilt the process against rights-holder claimants; a proposal that interested third parties may need to bear the costs of their participation, which may effectively skew such participation away from all but corporate third parties; and suggestions on interim measures that could place unfathomable responsibility on human rights victims