Glossary

Every term of art in the coded-magnet world, defined in one or two sentences.

Term	Definition
Maxel	A magnetic pixel — one small (~1 mm) region of chosen N or S polarity written into a magnet face by a single magnetizing pulse. The unit cell of every coded pattern.
Magnetic code	The designed spatial arrangement of maxel polarities on a magnet face; determines the part's entire force behavior.
Correlation	The signal-processing operation that gives coded magnets their behavior: net force between two coded faces tracks the spatial correlation of their codes — peak when matched and aligned, collapsed (~10× less) otherwise.
Correlated magnetics	CMR's name for the discipline: designing magnet pairs whose interaction is governed by code correlation.
Field emission structure	The patents' term (US 7,800,471) for a coded magnetic surface.
Spatial force function	The engineered force-vs-position curve of a coded pair — the thing you actually design. Can cross zero, change sign, hold detents.
Multipole	Any magnet with more than one pole pair on a face — includes simple alternating stripes (fridge magnets, encoder rings) and, as a special designed case, coded magnets.
Halbach array	A periodic rotating-magnetization arrangement that throws uniform flux out one side (Mallinson 1973, Halbach 1980s). Cousin to coding: periodic and field-shaping rather than aperiodic and force-function-shaping.
Near field / far field	The two regimes of a patterned surface: intense within a fraction of the pole pitch, decaying as e^(−2πz/λ) beyond. Fine pitch = strong and short; coarse = weaker and longer.
Barker code	Low-autocorrelation binary sequences from radar; used in the foundational patents because their off-peak sidelobes never exceed 1 — the property that makes alignment sharp and mismatch weak.
Polymagnet®	CMR's trademark for its coded magnets — the brand name; the company is Correlated Magnetics Research, Inc.
MagPrinter	CMR's magnetizing printer (2013; desktop Mini 2014): writes maxels one ~0.8 ms pulse at a time from a software pattern.
Spring / Latch / Align / Twist-Release / Attach / Shear / Torque / Detent	The eight catalog behaviors — see the full chapter with datasheet numbers.
Earnshaw's theorem	No static arrangement of permanent magnets can stably levitate an object free in space. Why every magnetic-spring demo rides a pin.
Energy product (MGOe)	The figure of merit for magnet material strength (NdFeB ~52 MGOe max). Coding redistributes this energy spatially; it cannot exceed it.
Electropermanent magnet	A magnet switchable on/off with a current pulse (Magswitch et al.) — "programmable in time," complementary to coding's "programmable in space."
Maxel pitch (λ)	Spacing of the maxel pattern; sets field reach via e^(−2πz/λ). The single most important design knob.
Viewing film	Magneto-optical film that makes a maxel pattern visible as a green-on-dark texture — the quickest way to see the code.
Remanence (Br)	The magnetic flux density a magnet keeps after the magnetizing field is removed; for sintered NdFeB roughly 1.0–1.4 tesla. Coding does not change a material’s remanence — only where that flux is directed.
Coercivity (Hc / Hcj)	How strongly a magnet resists being demagnetized by an opposing field or by heat. High-coercivity NdFeB grades matter for coded magnets because the printer writes opposing polarities millimetres apart without erasing their neighbours.
Neodymium (NdFeB)	The neodymium-iron-boron alloy behind most coded magnets — the strongest commercial permanent-magnet material, and the usual blank the MagPrinter re-magnetizes.
Pole pitch	The centre-to-centre spacing between opposite poles on a patterned face; effectively the maxel pitch. It sets how far the field reaches and how sharp the alignment is.
Autocorrelation / sidelobe	A measure of how a code matches shifted copies of itself. Low sidelobes (as in Barker codes) mean a coded pair grips hard only when correctly aligned and stays weak everywhere else.
Flux density (gauss / tesla)	The strength of a magnetic field at a point (1 tesla = 10,000 gauss). Coded faces show high flux right at the surface that falls away far faster than a conventional magnet’s.
Curie temperature	The temperature at which a material loses its permanent magnetism entirely; NdFeB’s is about 310–400 °C, though usable operating temperature is far lower and set by coercivity.
Anisotropy / easy axis	The preferred direction along which a material magnetizes. Sintered NdFeB is anisotropic, so a blank is pressed with its easy axis through the thickness before maxels are written on the face.
Sintered vs bonded magnet	Sintered NdFeB is fully dense and strongest; bonded (polymer-mixed) magnets are weaker but can be moulded to shape. Coded magnets are typically printed on sintered blanks.
Working gap / air gap	The designed distance between two magnet faces (or magnet and steel) at which a coded part is meant to operate. Coded magnets are specified for very small gaps, often under about 2 mm.
Shear vs normal force	Normal force acts along the axis (attract/repel); shear force resists sliding across the face. Coded patterns can be designed strong in one and deliberately weak in the other.
Detent	A designed set of stable angular or linear positions a coded pair snaps to — the basis of haptic dials and multi-position knobs.
Keying (magnetic key)	A code unique enough that a part only mates with its intended partner and ignores or repels the wrong one — a mechanical “password” with no electronics.
Polyvision (design software)	CMR’s tool for laying out maxel patterns and simulating the resulting force curve before a part is printed.
Magnetizer / fixture	The coil-and-capacitor hardware that delivers the high-current pulse writing each maxel. The MagPrinter is a CNC-style magnetizer that places those pulses from a file.
Demagnetization curve	The second-quadrant B–H curve describing how a magnet behaves against an opposing field; where a magnet “sits” on it (its working point) determines stability in a given circuit.

Where do these definitions come from? Sources & further reading →

Glossary

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