Detection of Short-Waved Spin Waves in Individual Microscopic Spin-Wave Waveguides Using the Inverse Spin Hall Effect

The miniaturization of complementary metal-oxide-semiconductor (CMOS) devices becomes increasingly difficult due to fundamental limitations and the increase of leakage currents. Large research efforts are devoted to find alternative concepts that allow for a larger data-density and lower power consumption than conventional semiconductor approaches. Spin waves have been identified as a potential technology that can complement and outperform CMOS in complex logic applications, profiting from the fact that these waves enable wave computing on the nanoscale. The practical application of spin waves, however, requires the demonstration of scalable, CMOS compatible spin-wave detection schemes in material systems compatible with standard spintronics as well as semiconductor circuitry. Here, we report on the wave-vector independent detection of short-waved spin waves with wavelengths down to 150 nm by the inverse spin Hall effect in spin-wave waveguides made from ultrathin Ta/Co₈Fe₇₂B₂₀/MgO. These findings open up the path for miniaturized scalable interconnects between spin waves and CMOS and the use of ultrathin films made from standard spintronic materials in magnonics.

Chirality-Induced asymmetric magnetic nucleation in Pt/Co/AlOx ultrathin microstructures

The nucleation of reversed magnetic domains in Pt/Co/AlO(x) microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field.

Domain wall tilting in the presence of the Dzyaloshinskii-Moriya interaction in out-of-plane magnetized magnetic nanotracks

We show that the Dzyaloshinskii-Moriya interaction (DMI) can lead to a tilting of the domain wall (DW) surface in perpendicularly magnetized magnetic nanotracks when DW dynamics are driven by an easy axis magnetic field or a spin polarized current. The DW tilting affects the DW dynamics for large DMI, and the tilting relaxation time can be very large as it scales with the square of the track width. The results are well explained by an extended collective coordinate model where DMI and DW tilting are included. We propose a simple way to estimate the DMI in magnetic multilayers by measuring the dependence of the DW tilt angle on a transverse static magnetic field. These results shed light on the current induced DW tilting observed recently in Co/Ni multilayers with structural inversion asymmetry.

Direct observation of massless domain wall dynamics in nanostripes with perpendicular magnetic anisotropy

Domain wall motion induced by nanosecond current pulses in nanostripes with perpendicular magnetic anisotropy (Pt/Co/AlO(x)) is shown to exhibit negligible inertia. Time-resolved magnetic microscopy during current pulses reveals that the domain walls start moving, with a constant speed, as soon as the current reaches a constant amplitude, and no or little motion takes place after the end of the pulse. The very low "mass" of these domain walls is attributed to the combination of their narrow width and high damping parameter α. Such a small inertia should allow accurate control of domain wall motion by tuning the duration and amplitude of the current pulses.

Domain wall spin torquemeter

We report the direct measurement of the nonadiabatic component of the spin torque in domain walls. Our method is independent of both the pinning of the domain wall in the wire as well as of the Gilbert damping parameter. We demonstrate that the ratio between the nonadiabatic and the adiabatic components can be as high as 1, and explain this high value by the importance of the spin-flip rate to the nonadiabatic torque. In addition to their fundamental significance these results open the way for applications by demonstrating a significant increase of the spin torque efficiency.

[Ovarian cancer: the symptoms and pathology. The cases of the Cantonal Cancer Registry (1989-1995)]

BACKGROUND

Ovarian cancer is most frequently discovered at an advanced stage. The absence of symptoms in the early stages is thought to be the main reason for this late discovery. We tried to determine whether there are any specific signs or symptoms for early or late stages.

METHODS

From 1989 to 1995, the Cantonal Cancer Registry recorded 124 patients with ovarian cancer; 119 (96%) cases were evaluated. We defined signs and symptoms which led to the diagnosis, their histopathological properties and the medical specialty of the physician first consulted. The data were then analyzed for early stages (IA to IB) (n = 27) and advanced stages (IC to IV) (n = 92).

RESULTS

In the early as well as late stages, the most common symptoms were abdominal pain (76%) and gastrointestinal problems (45%). Bladder and gynecological symptoms were rare (25% and 7% respectively). In the early stages, however, the ovarian tumor was larger (median size 14 vs 11 cm), there were more well differentiated tumors (48% G1 vs 25%) and the age was lower (median age 55 vs 66 years). The physician first consulted was a general practitioner in 2/3 (68%) of the cases and a gynecologist in 17%.

CONCLUSIONS

There are no specific ovarian carcinoma symptoms either in the early or in the late stages. The histology showed that tumors in the early stages were less aggressive and usually occurred in younger patients. The general practitioner was most often the first physician consulted by women suffering from ovarian cancer. General practitioners, therefore, should be specialists in the diagnosis of this disease, paying particular attention to women over 40 presenting with persistent abdominal pain.