Spin-spiral states in undoped manganites

The experimental observation of multiferroic behavior in perovskite manganites with a spiral spin structure demands to clarify the origin of these magnetic states and their relation to ferroelectricity. We show that spin-spiral phases with diagonal wavevector and also the E-type phase exist for intermediate values of the Hund's rule and the Jahn-Teller coupling in the orbitally ordered and insulating state of the standard two-band model Hamiltonian for manganites. Our results support the spin-current mechanism for ferroelectricity and present an alternative view to earlier conclusions where frustrating superexchange couplings were crucial to obtain spin-spiral states.Comment: typos fixed, figures 2 and 3 modifie

Asymmetric magnetic bubble expansion under in-plane field in Pt/Co/Pt: effect of interface engineering

We analyse the impact of growth conditions on asymmetric magnetic bubble expansion under in-plane field in ultrathin Pt / Co / Pt films. Specifically, using sputter deposition we vary the Ar pressure during the growth of the top Pt layer. This induces a large change in the interfacial structure as evidenced by a factor three change in the effective perpendicular magnetic anisotropy. Strikingly, a discrepancy between the current theory for domain-wall propagation based on a simple domain-wall energy density and our experimental results is found. This calls for further theoretical development of domain-wall creep under in-plane fields and varying structural asymmetry.Comment: 16 pages, 3 figure

Familiarity between patient and general practitioner does not influence the content of the consultation

<p>Abstract</p> <p>Background</p> <p>Personal continuity in general practice is considered to be a prerequisite of high quality patient care based on shared knowledge and mutual understanding. Not much is known about how personal continuity is reflected in the content of GP – patient communication. We explored whether personal continuity of care influences the content of communication during the consultation.</p> <p>Methods</p> <p>Personal continuity was defined as the degree of familiarity between GP and patient, rated by both the GP and the patient. 394 videotaped consultations between GPs and patients aged 18 years and older were analyzed. GP – patient communication was evaluated with an observation checklist, which rated the following topics of conversation: (1) medical issues, (2) psychological themes, and (3) the social environment of the patient. For each of these topics we coded whether or not it received attention, and was built upon prior knowledge. Data were analyzed using multilevel logistic regression analyses.</p> <p>Results</p> <p>No relationship was found between GP – patient familiarity and the discussion of medical issues, psychological themes, or the social environment of the patient. But if the patient and the GP knew each other very well, the GP more often displayed prior knowledge with the topic in question. Few patient and GP characteristics were associated with differences in content of communication.</p> <p>Conclusion</p> <p>Given the relatively small sample size, we carefully conclude that familiarity between a GP and a patient does not influence the content of the communication (medical issues, psychological themes nor topics relating to the social environment). This is remarkable because we expected that familiarity would 'open up the communication' for more psychological and social themes. GPs seem to have the communication skills to put both familiar and non-familiar patients at ease enabling them to freely raise any issue they think necessary.</p

Electric-field control of domain wall motion in perpendicutlarly magnetiezed materials

Domain wall motion in materials exhibiting perpendicular magnetic anisotropy has been the subject of intensive research because of its large potential for future spintronic devices. Recently, it has been shown that perpendicular anisotropy of thin films can be influenced by electric fields. Voltage-controlled magnetic switching has already been realized, which is envisioned to lead to low-power logic and memory devices. Here we demonstrate a radically new application of this effect, namely control of domain wall motion by electric fields. We show that an applied voltage perpendicular to a Co or CoB wire can significantly increase or decrease domain wall velocities. Velocity modification over an order of magnitude is demonstrated (from 0.4 to 4 µm s(-1)), providing a first step towards electrical control of domain wall devices. This opens up possibilities of real-time and local control of domain wall motion by electric fields at extremely low power cost

Spin-Hall assisted magnetic random access memory

We propose a write scheme for perpendicular spin-transfer torque magnetoresistive random-access memory that significantly reduces the required tunnel current density and write energy. A sub-nanosecond in-plane polarized spin current pulse is generated using the spin-Hall effect, disturbing the stable magnetic state. Subsequent switching using out-of-plane polarized spin current becomes highly efficient. Through evaluation of the Landau-Lifshitz-Gilbert equation, we quantitatively assess the viability of this write scheme for a wide range of system parameters. A typical example shows an eight-fold reduction in tunnel current density, corresponding to a fifty-fold reduction in write energy, while maintaining a 1¿ns write time

Field-free magnetization reversal by spin-Hall effect and exchange bias

As the first magnetic random access memories are finding their way onto the market, an important issue remains to be solved: the current density required to write magnetic bits becomes prohibitively high as bit dimensions are reduced. Recently, spin–orbit torques and the spin-Hall effect in particular have attracted significant interest, as they enable magnetization reversal without high current densities running through the tunnel barrier. For perpendicularly magnetized layers, however, the technological implementation of the spin-Hall effect is hampered by the necessity of an in-plane magnetic field for deterministic switching. Here we interface a thin ferromagnetic layer with an anti-ferromagnetic material. An in-plane exchange bias is created and shown to enable field-free S HE-driven magnetization reversal of a perpendicularly magnetized Pt/Co/IrMn structure. Aside from the potential technological implications, our experiment provides additional insight into the local spin structure at the ferromagnetic/anti-ferromagnetic interface\u3cbr/\u3