Volume 77, Issue 3, March 2006
Index of content:
- ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES
Design of a modular and versatile interlock system for ultrahigh vacuum machines: A crossed molecular beam setup as a case study77(2006); http://dx.doi.org/10.1063/1.2173074View Description Hide Description
The design of a modular, versatile interlock system for ultrahigh vacuum machines is presented. This system can monitor the pressure (ultrahigh vacuum and high vacuum), the status of the power (power failure, power fluctuations, and scheduled power outages), the operation mode of the pumps (operation versus failure), the flow of cooling water, the humidity and temperature levels in the laboratory, as well as the concentration of toxic gases. If any of the set points is triggered, the vacuum machine is protected fully automatically. The interlock system is also interfaced to an automated paging system, thus transmitting a pager signal to the person on duty. Since the interlock system is modular in nature, it can be expanded and be adapted stepwise to incorporate additional safety and monitoring functions as needed.
77(2006); http://dx.doi.org/10.1063/1.2185149View Description Hide Description
We have developed a new method for measuring the value of breakdown voltage in air for electrode separations from . The electrodes used were thin film Au lines evaporated on sapphire. The resulting capacitors had an area of . We demonstrate the ability to deduce the value of the separation of the plates by the value of the capacitance. The data acquired with this method do not agree with Paschen’s law for electrode separations below , as expected from previous experiments. Amongst the improvements of our method are the measurement of plate separation and the very small surface roughness (average of ).
77(2006); http://dx.doi.org/10.1063/1.2185147View Description Hide Description
Heat assisted magnetic recording is proposed to be a candidate to overcome superparamagnet effect and support recording. However, laser heating technique induces serious challenges to build a reliable and stable head-disk interface. One of them is how to measure the temperature in the disk magnetic layer of which thickness is around the nanometer level and in a slider giant magnetoresistive (GMR)sensor. In this article, we propose a novel method to measuretemperature in magnetic media and slider of GMRsensor. It combines material characterization by vibration scanning magnetometer and read/write performance characterization of magnetic head and disk on spin stand. Experimental results of temperature rise in the slider and locally heated region in a magnetic disk are presented. Under various laser power irradiations,glass substrate disks with/without magnetic recording layer (on one side) were used. All experiments were performed on Guzik spin stand with an attached optical system. Results indicate that the heat transfers not only from the slider to the air bearing surface but also from the locally heated magnetic disk to the slider through the air bearing. The heat distribution on the slider depends on the slider material and the laser beam location. The results also show that the resistance variation in the GMRsensor could be a good indicator to monitor slider flying height fluctuation in the future.
Component-resolved determination of the magnetization by magnetization-induced optical second-harmonic generation77(2006); http://dx.doi.org/10.1063/1.2179414View Description Hide Description
We present a method for simultaneously measuring the two normalized in-plane magnetization components in magnetic thin films that allows for the reconstruction of the magnetization angle and the normalized value of the magnetization with subnanosecond temporal resolution. The calibrated method relies on the large contrast associated with magnetization-induced optical second-harmonic generation, permitting measurements with a dynamic range in excess of . Calibration is achieved by the determination of the relative magnitude and phase of the essential nonlinear optical tensor components, including those of a magneto-optic origin. Ellipsometric determination of the polarization of the second-harmonic signal, when the magnetization is saturated along four in-plane Cartesian directions, is sufficient to determine the second-order nonlinear tensor components. These four directions represent the two saturated states along the longitudinal and transverse directions of the magnetization, respectively. The tensor components are subsequently used to uniquely determine the in-plane magnetization amplitude and direction.