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We have fabricated a superconducting resonator capable of generating a strong microwave magnetic field in a small (100 μm) volume for low temperature magnetic resonance experiments. While the resonator was specifically developed for use at millikelvin temperatures in a dilution refrigerator, where the total cooling power is limited to a few hundred microwatts, it is also useful at temperatures up to 5 K. The resonator consists of a 220 μm diameter, 2-1/2 turn niobium coil resonating with a short section of niobium microstripline. At a resonance frequency of 3 GHz, the loaded Q of the resonator was 780. The field strength was characterized by performing electron spin nutations. Operating at 100 mK with 320 μW of dissipated power, the resonator generated a field of 4 G at a distance of 100 μm from the coil.

Using the stimulated Brillouin scattering phase conjugation and pulse compression technique, a conventional long pulse ruby laser was successfully converted to give 300 ps pulses at 1 J energy level. The technique allows the use of smaller amplifiers than required in a conventional short pulse laser which in turn leads to operation at increased repetition rate. The completed laser when operated at 1.5 Hz produces stable output parameters. Each laser pulse is characterized by a sharp rise and a measured pre‐pulse level of less than 10−6 of the main pulse, making it suitable for LIDAR Thomson scattering measurements.

A fast scanning tunneling microscope (STM) for scanning micron‐sized areas of atomically rough surfaces has been developed. The response time of the feedback loop controlling the tip‐sample spacing is roughly 5 μs, and the maximum scan velocity is 1 mm/s. The instrument uses fast electronics and a novel mechanical design to achieve the high bandwidth. The high bandwidth makes the STM capable of nearly real‐time panning and zooming, allowing for rapid searches over the surface of the sample. The instrument has been used in air to study wear of atomic layers, and also to perform nanowriting while scanning. In the case of the wear study, it was found that step edges not only can retreat during wear, but can also advance.

A 290-nm-thick single-crystal silicon cantilever has been cooled in vacuum to a temperature of 110 mK in order reduce its thermal motion and thereby improve the achievable force resolution. Since the thermal conductivity of the silicon cantilever is extremely low at millikelvin temperatures, an improved optical fiber interferometer was developed to measure the subangstrom thermal motion with optical powers as low as 2 nW. At the lowest temperature, the cantilever exhibited a quality factor of 150 000 and achieved a noise temperature of 220 mK, with a corresponding force noise of 820 zN in a 1 Hz bandwidth.

Conductance versus voltage and capacitance versus voltage (C–V) characteristics are investigated for p+–p−–p+ capacitors over a temperature range of 40–300 K, where the p+ layer is heavily doped homoepitaxial diamond and has impurity-band conduction and the p− layer is slightly doped with valence-band conduction. Above 200 K, the capacitors behave like a semiconductor–insulator–semiconductor diode with interface barrier height of about 0.07 eV. The C–V curve agrees closely with the standard theory of semiconductor–insulator–semiconductor structure and shows formation of the deletion layer at the p+ layer on the interface. The Cole–Cole plot of conductance versus susceptance reveals that there is a virtual trap level in the p− layer which is located about 0.06 eV above the valence band.

This paper discusses the principles of magnetic force microscopy (MFM) and its application to magnetic recording studies. We use the ac detection method which senses the force gradient acting on a small magnetic tip due to fields emanating from the domain structure in the sample. Tip fabrication procedures are described for two types of magnetic tips: etched tungsten wires with a sputter‐deposited magnetic coating and etched nickel wires. The etched nickel wires are shown to have an apex radius on the order of 30 nm and a taper half‐angle of approximately 3°. Lorentz‐mode transmission electron microscopy of the nickel tips reveals that the final 20 μm is essentially single domain with magnetization approximately parallel with the tip axis. Images of written bit transitions are presented for several types of magnetic media, including CoPtCr, CoSm, and CoCr thin films, as well as γ‐Fe2O3 particulate media. In general, the written magnetization patterns are seen with high contrast and with resolution better ...

We report a simple atomic force microscopy-based concept for a hard disk-like data storage technology. Thermomechanical writing by heating a Si cantilever in contact with a spinning polycarbonate disk has already been reported. Here the medium has been replaced with a thin polymer layer on a Si substrate, resulting in significant improvements in storage density. With this new medium, we achieve bit sizes of 10–50 nm, leading to data densities of 500 Gbit/in.2. We also demonstrate a novel high-speed and high-resolution thermal readback method, which uses the same Si cantilevers that are used in the writing process, and the capability to erase and rewrite data features repeatedly.

It is shown that creation of local charged states at the surface of the lanthanum-strontium manganite single crystals by means of bias application via a conducting atomic force microscope tip is strongly affected by magnetic field. Both a charge and a size of created structures increase significantly on application of the magnetic field during the induction. We argue that the observed phenomenon originates from a known tendency of manganites toward charge segregation and its intimate relation to magnetic ordering.

A technique for detecting strain has been demonstrated based on a spin-valve sensor. The 400 A thick sensor has been integrated onto an atomic force microscope cantilever. An applied strain caused by bending of the cantilever changes the orientation of the free-layer magnetization due to magnetostriction. This in turn results in a change in the electrical resistance because of the giant magnetoresistance effect. With the proper magnetic bias, a base-line strain sensitivity of 10−10/Hz1/2 has been achieved. The corresponding gauge factor of 150 is roughly 1.6× that of similar silicon piezoresistive cantilevers. In the future, one might be able to enhance the sensitivity by another factor of 3–5.

A dual-axis atomic force microscope (AFM) cantilever with independent piezoresistive sensors has been developed for simultaneous detection of vertical and lateral forces. The cantilever consists of a flat, triangular probe connected to a base by four tall, narrow ribs. The vertically compliant triangular probe and the laterally compliant ribs incorporate separate piezoresistors for vertical and lateral force sensing. In the fabrication process, a special oblique ion implant technique is used to produce electrical elements on vertical sidewalls and horizontal surfaces of the cantilever structure at the same time. The dual-axis cantilever has been used to perform microfriction measurements as well as obtain simultaneous vertical-force and lateral-force AFM images.

Recently, there have been significant advances in demonstrating the possible application of scanning probe techniques for high density data storage. While many obstacles have yet to be overcome, one of the more promising applications of such devices is for very high density read‐only disk drives. Such an application requires the means to pattern and replicate nanometer scale features over macroscopic dimensions. We have developed a technique for both mastering and replicating data patterns for use in such a device at a density 100 times that of current read‐only disks. The process consists of using electron beam lithography to write data features as small as 50 nm and a photopolymerization process to faithfully replicate the written marks.

Low‐stiffness silicon cantilevers have been developed for proposed data storage devices based on the atomic force microscope, in particular thermomechanical recording. The cantilevers combine a sharp tip with an integrated piezoresistive sensor for data readback from a rotating polycarbonate disk. A novel process was developed to make shallow piezoresistors in cantilevers 1 μm thick, significantly thinner and therefore softer than previously possible. Readback was demonstrated at linear velocities up to 120 mm/s. Separate cantilevers with resistively heated tips were fabricated for writing data marks on polycarbonate, with measured thermal time constants of 30 μs.

Resistive heating of an atomic force microscope tip was used to perform thermally induced surface modifications. Heating was achieved by dissipating power in the legs of an electrically conducting silicon cantilever. Temperatures of up to 170 °C were obtained using 40 mW of input power. Electrical measurements used to monitor the temperature showed thermal time constants of 0.35–0.45 ms, depending on whether the tip was in contact with a substrate. The heated tip was used to demonstrate thermomechanical writing on a polycarbonate substrate, as well as thermal writing of an optical phase change material.

A recently developed near‐field optical technique, the solid immersion lens (SIL), is utilized in a realistic demonstration of near‐field optical data storage. Using 830 nm light, a 360 nm optical spot size is obtained at the exit surface of the SIL and is transferred across a small air gap to the surface of a spinning magneto‐optical disk. Reading and writing of data are achieved at a density of 3.8× 108 bits/cm2 with a data rate of 3.3×106 bits/s. The subwavelength gap between the lens and the disk is maintained at a media velocity of 1.25 m/s by incorporating the lens into an air‐bearing slider.

A near‐field optical technique, using a new type of solid immersion lens (SIL), has been developed and applied to the writing and reading of domains in magneto‐optic material. The SIL is a truncated glass sphere which serves to increase the numerical aperture of the optical system by n2, where n is the index of refraction of the lens material. Using a SIL made from n=1.83 glass and illuminating with 780 nm light, we have achieved a 317 nm spot size. We have resolved a 500 nm period grating, and written and read 350 nm diameter magnetic domains. The technique should be capable of a 125 nm focused spot size using blue light.

We have developed a simple and fast surface modification technique for possible data storage applications. Writing is accomplished by heating the metallized tip of a tapered optical fiber with microsecond laser pulses. The heated tip, which is in contact with a polycarbonate substrate, creates a nanoindentation. Deflections of this same tip are used to detect the written marks, as in atomic force microscopy. The marks have sharp edges with 10%–90% transition widths of 0.2 μm, and have been written with laser pulses as short as 5 μs at repetition rates of 50 kHz. Readback has been performed over 300 kHz on a spinning sample. Substantial improvements in mechanical response and wear properties are seen compared to micromachined cantilevers.

We investigate the effect of two different surface treatments on shallow nitrogen-vacancy (NV) centers in diamond. Short duration oxygen plasma exposure is found to damage near-surface NV centers, resulting in their disappearance in fluorescence images. Subsequent annealing creates large numbers of new NV centers, attributed to plasma-induced vacancy creation. By tracking individual NV centers during thermal oxidation, we show that oxidation at 550 °C results in modest improvement of spin coherence. Higher temperature oxidations correlate with gradual decline in spin coherence and eventual instability of NV centers before ultimate disappearance. This is indicative of a reduction of the NV-to-surface distance due to oxidative etching. Thermal oxidation can offer controlled access to near-surface NV spins at the nanometer scale, an important requirement for many applications of NV-based nanomagnetometry.

We have developed a new technique to perform fast, reliable nanoindentation of polymer surfaces for possible applications to high density data storage. In this technique, an infrared laser is focused on an atomic force microscope (AFM) tip, which is in contact with a transparent polymethyl methacrylate (PMMA) substrate. The heat from the tip softens the PMMA in the contact region, at which point the local tip pressure creates a pit. The pits range in size from several hundred angstroms to 1 μm, depending on the size of the laser pulse and the loading force on the tip. Pits have been made with pulses as short as 0.3 μs at loads of 10−7 N. By operating the AFM on a rotating disk, we have shown that the features can be written and read at frequencies up to at least 100 kHz.

In this paper the properties of force sensors suitable for magnetic force microscopy (MFM) made by coating silicon microcantilevers with various thin magnetic films are analyzed. These MFM force sensors are batch fabricated and their magnetic properties controlled by choosing appropriate coatings. Theoretical calculations show that thin‐film MFM tips have a significantly reduced stray field, a good signal‐to‐noise ratio, and yield improved resolution when compared to etched wire tips. The sample perturbation due to the tip stray field is small, allowing the imaging of low‐coercivity samples such as Permalloy.

In this letter we describe force sensors suitable for magnetic force microscopy (MFM) made by coating silicon microcantilevers with various thin magnetic films. These MFM force sensors can be batch fabricated and their magnetic properties tailored by choosing appropriate coatings. This is demonstrated by analyzing the MFM response for magnetization patterns written on a longitudinal recording test sample. Selectable components of the sample stray field can be measured by coating the tips with high coercivity films. Tips coated with low coercivity films such as Permalloy respond to the total stray field. Sample perturbations due to the tip stray field are small for thin‐film tips, allowing the imaging of low coercivity samples such as Permalloy.

Magnetic resonance force microscopy (MRFM) is based on measuring the attonewton-scale force between nuclear or electronic spins and a magnetic tip. The force is directly proportional to the magnetic field gradient generated by the tip, making a high moment nanoscale magnet desirable. Dysprosium, with a bulk magnetization 70% higher than iron, is a suitable candidate for such a tip. We have performed MRFM to quantitatively characterize two Dy nanomagnets. We find that magnetic field gradients as high as 6 MT/m (60 G/nm) can be generated, a 40% enhancement compared to our previous FeCo tips.

Scanning probe microscopy was used to create and to detect local bias induced charged states in La0.89Sr0.11MnO3 single crystals at room temperature. The lifetime of these nonequilibrium states exceeds 100 h. These bias induced states display also a ferroelectriclike hysteresis with piezoelectric contrast reversed by the applied field. Such states showing reversible multifunctional properties are attractive for modern semiconductor technology with its focus on nonvolatile random-access memories.

The authors show that the phase of a high-Q cantilever can be reversed abruptly, and they use this capability to detect spins for magnetic resonance force microscopy. Spins are manipulated at the cantilever resonant frequency while driving the cantilever with a wave form that has no Fourier component at this frequency. This amplitude-based detection protocol is motivated by the desire to avoid the effects of surface-induced force noise, which can interfere with frequency-based detection schemes. The technique has been applied to the detection of E′ centers and has shown significantly reduced susceptibility to surface noise, resulting in improved signal-to-noise ratio.