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1.
Phys Rev Lett ; 117(5): 057201, 2016 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-27517790

RESUMEN

We report a comparative study of magnetic field driven domain wall motion in thin films made of different magnetic materials for a wide range of field and temperature. The full thermally activated creep motion, observed below the depinning threshold, is shown to be described by a unique universal energy barrier function. Our findings should be relevant for other systems whose dynamics can be modeled by elastic interfaces moving on disordered energy landscapes.

2.
Phys Rev Lett ; 113(2): 027205, 2014 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-25062227

RESUMEN

Magnetic-field-driven domain wall motion in an ultrathin Pt/Co(0.45 nm)/Pt ferromagnetic film with perpendicular anisotropy is studied over a wide temperature range. Three different pinning dependent dynamical regimes are clearly identified: the creep, the thermally assisted flux flow, and the depinning, as well as their corresponding crossovers. The wall elastic energy and microscopic parameters characterizing the pinning are determined. Both the extracted thermal rounding exponent at the depinning transition, ψ=0.15, and the Larkin length crossover exponent, ϕ=0.24, fit well with the numerical predictions.

3.
Phys Rev Lett ; 112(2): 026601, 2014 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-24484033

RESUMEN

We show experimental evidence of magnetization switching in a single (Ga,Mn)(As,P) semiconducting ferromagnetic layer, attributed to a strong reduction of the magnetization and the anisotropy due to current injection. The nucleation of magnetization reversal is found to occur even in the absence of a magnetic field and to be both anisotropic and stochastic. Our findings highlight a new mechanism of magnetization manipulation based on spin accumulation in a semiconductor material.

4.
Phys Rev Lett ; 108(7): 076604, 2012 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-22401234

RESUMEN

Current-driven domain-wall motion is studied in (Ga,Mn)(As,P) ferromagnetic semiconducting tracks with perpendicular anisotropy. A linear steady state flow regime is observed over a large temperature range of the ferromagnetic phase (0.1T(c)

5.
J Phys Condens Matter ; 23(44): 446004, 2011 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-22005254

RESUMEN

Domain wall dynamics produced by spin transfer torques is investigated in (Ga, Mn)As ferromagnetic semiconducting tracks with perpendicular anisotropy, close to the Curie temperature. The domain wall velocities are found to follow a linear flow regime which only slightly varies with temperature. Using the Döring inequality, boundaries of the spin polarization of the current are deduced. A comparison with the predictions of the mean field k·p theory leads to an estimation of the carrier density whose value is compatible with results published in the literature. The spin polarization of the current and the magnetization of the magnetic atoms present similar temperature variations. This leads to a weak temperature dependence of the spin drift velocity and thus of the domain wall velocity. A combined study of field- and current-driven motion and deformation of magnetic domains reveals a motion of domain walls in the steady state regime without transition to the precessional regime. The ratio between the non-adiabatic torque ß and the Gilbert damping factor α is shown to remain close to unity.

6.
Phys Rev Lett ; 96(8): 087002, 2006 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-16606216

RESUMEN

The phase transition between the intermediate and normal states in type-I superconducting films is investigated using magneto-optical imaging. Magnetic hysteresis with different transition fields for collapse and nucleation of superconducting domains is found. This is accompanied by topological hysteresis characterized by the collapse of circular domains and the appearance of lamellar domains. Magnetic hysteresis is shown to arise from supercooled and superheated states. Domain-shape instability resulting from long-range magnetic interaction accounts well for topological hysteresis.

7.
Phys Rev Lett ; 92(14): 147001, 2004 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-15089565

RESUMEN

Normal state bubble patterns in type I superconducting indium and lead slabs are studied by the high resolution magneto-optical imaging technique. The size of bubbles is found to be independent of the long-range interaction between the normal state domains. Under bubble diameter and slab thickness proper scaling, the results gather onto a single master curve. We calculate the equilibrium diameter of an isolated bubble resulting from the competition between the Biot-and-Savart interaction of the Meissner current encircling the bubble and the superconductor-normal interface energy. A good quantitative agreement with the master curve is found over two decades of the magnetic Bond number. The isolation of each bubble in the superconductor and the interface energy are shown to preclude any continuous size variation of the bubbles after their formation, contrary to the prediction of mean-field models.

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