The weakness of the force of gravity compared to the electromagnetic force and the other fundamental forces has been referred to as the hierarchy problem. If gravity propagates in several additional spatial dimensions that are large compared to the Planck scale, the hypothesis is that gravity is stronger close-up, e.g., below a certain interaction distance the force of gravity is magnified. In the hard disk drive assembly, the magneto-resistor (MR) read sensor in the head assembly operates within 100nm of the spinning disk surface. Fourteen variable size nano-bumps and nano-pits were fabricated on a magnetic disk platen’s surface designed to be less than the Planck mass 21.77 μgrams. These nano-features were measured over the spinning disk with both piezoelectric and MR sensors. The data was validated using both atomic force microscope (AFM) and magnetic force microscope (MFM) measurements. Results are reviewed and theoretical implications are discussed. The results suggest that the force of gravity is magnified and there are two forms of gravitation. Implications to modified spacetime are discussed.

In a disk drive magnetic read/write is achieved with a magnetic head flying closely over a magnetic disk. As area 1 recording density is increased to several Gbits/In2, the dynamic flying height of the magnetic head is reduced to one (mu) -inch or less. Bumps taller than one (mu) -inch often results in head crash. Since the DLC coating on the magnetic disk surface is less than 10 nanometers in thickness, pits with depth over 10 nanometers cause damage to the magnetic layer. To prevent head crash or missing bit errors, magnetic disk surface needs to be examined for bumps taller than the dynamic flying height and pits deeper than the DLC thickness. In this paper, we report experimental results using a head with an MR sensor flying over a disk with precision bumps and pits micro-fabricated on the disk surface. Non-contact signal disturbances of the MR sensor flown over variable area square pits and bumps on the 2400 Oe media exhibit both magnetic and thermal signal characteristics. The lateral sizes of the pits and bumps obtained using the MR magnetic signal measured from a Phase Metrics MG250 tester agree well with those measured with an Atomic Force Microscope (AFM). The thermal signal characteristics of the pits and bumps are of opposite polarity, and scale in a non-linear fashion with the lateral size of the surface defects. Some preliminary experimental results involving naturally occurring surface defects and Phase Metrics' optical scatterometry tester PS5100 are also discussed for comparison purposes.

The quantitative effects of dislocations on the electrical and optical properties of long-wavelength infrared (LWIR) HgCdTe photovoltaic detectors was determined by deliberately introducing dislocations into localized regions of two high-performance arrays having cutoff wavelengths of 9.5 and 10.3 μm at T=78 K. Results show that dislocations can have a dramatic effect on detector R0A product, particularly at temperatures below 78 K. For large dislocation densities, R0A decreases as the square of the dislocation density; the onset of the square dependence occurs at progressively lower dislocation densities as the temperature decreases. A phenomenological model was developed which describes the dependence of the detector R0A product with dislocation density, based on the conductances of individual and interacting dislocations which shunt the p–n junction. Spectral response and quantum efficiency are only weakly affected, as is the diffusion component of the leakage current. The 1/f noise current was found to increase approximately linearly with dislocation density and also tracks with the magnitude of the leakage current similar to a data trendline established for undamaged HgCdTe detectors. These results can be used to understand the performance limitations of LWIR HgCdTe arrays fabricated on heteroepitaxial substrates.