DNA is a compelling alternative to non-volatile information storage technologies due to its information density, stability, and energy efficiency. Previous studies have used artificially synthesized DNA to store data and automated next-generation sequencing to read it back. Here, we report digital Nucleic Acid Memory (dNAM) for applications that require a limited amount of data to have high information density, redundancy, and copy number. In dNAM, data is encoded by selecting combinations of single-stranded DNA with (1) or without (0) docking-site domains. When self-assembled with scaffold DNA, staple strands form DNA origami breadboards. Information encoded into the breadboards is read by monitoring the binding of fluorescent imager probes using DNA-PAINT super-resolution microscopy. To enhance data retention, a multi-layer error correction scheme that combines fountain and bi-level parity codes is used. As a prototype, fifteen origami encoded with ‘Data is in our DNA!\n’ are analyzed. Each origami encodes unique data-droplet, index, orientation, and error-correction information. The error-correction algorithms fully recover the message when individual docking sites, or entire origami, are missing. Unlike other approaches to DNA-based data storage, reading dNAM does not require sequencing. As such, it offers an additional path to explore the advantages and disadvantages of DNA as an emerging memory material.

The magnetomechanical properties of ferromagnetic shape memory alloy Ni-Mn-Ga single crystals depend strongly on the twin microstructure, which can be modified through thermomagnetomechanical training. Atomic force microscopy ͑AFM͒ and magnetic force microscopy ͑MFM͒ were used to characterize the evolution of twin microstructures during thermomechanical training of a Ni-Mn-Ga single crystal. Experiments were performed in the martensite phase at 25°C and in the austenite phase at 55°C. Two distinct twinning surface reliefs were observed at room temperature. At elevated temperature ͑55°C͒, the surface relief of one twinning mode disappeared while the other relief remained unchanged. When cooled back to 25°C, the twin surface relief recovered. The relief persisting at elevated temperature specifies the positions of twin boundaries that were present when the sample was polished prior to surface characterization. AFM and MFM following thermomechanical treatment provide a nondestructive method to identify the crystallographic orientation of each twin and of each twin boundary plane. Temperature dependent AFM and MFM experiments reveal the twinning history thereby establishing the technique as a unique predictive tool for revealing the path of the martensitic and reverse transformations of magnetic shape memory alloys.

With current non-volatile memory technology approaching intrinsic storage density limits, new data storage technologies are under development. Probe-based storage systems provide alternatives to conventional mass storage technologies. Ni-Mn-Ga, a ferromagnetic shape memory alloy (FSMA), is proposed as a medium for multi-bit storage using scanning probe microscopy (SPM) techniques. Local modifications of the magnetic stray field were achieved using nanoindentation. Magnetic poles collect within the indentation, which is leveraged to control the magnetic stray field for the patterning of magnetic information. Four magnetic-based memory states are possible due to magnetic field or stress-induced twin rearrangement along two crystal orientations, each with two possible magnetic orientations

Instrumented indentation was combined with microscopy and spectroscopy analysis to investigate the local mechanically induced ferroelectric to anti‐ferroelectric phase transformation of niobium‐modified lead zirconate titanate 95/5. Indentation experiments to a depth of 2 μm were performed using a Berkovich pyramidal three‐sided diamond tip. Subsequent Raman spectroscopy and piezoelectric force microscopy revealed that indentation locally induced the ferroelectric to antiferroelectric phase transformation. Piezoelectric force microscopy demonstrated the ability to map the individual phases within and near indented regions on the niobium‐modified lead zirconate titanate ceramics.