In an experiment that sounds almost too strange to be true, researchers working on the Greek island of Crete report that a thoroughly ordinary paramagnetic powder — a substance so weakly magnetic that its contribution to an external field is normally computed in fractions of a microtesla — appears to have been transformed into a weak ferromagnet, simply by exposing it to a magnetic field whose flux lines corkscrew through space at one very particular angle: 54.74 degrees, the celebrated “magic angle” of mathematics and magnetic resonance. According to the study, published in the journal Results in Physics, a 36-milligram sample of DPPH, the organic free radical used worldwide to calibrate electron paramagnetic resonance spectrometers, apparently underwent a genuine magnetic phase transition inside a purpose-built helical solenoid. The powder emerged with a relative magnetic permeability of roughly 1.4 instead of its textbook value of about 1.0001 and, more puzzling still, retained enough remanent magnetization to be visibly attracted to a permanent magnet a full hour after the current had been switched off.
To appreciate why the claim is so provocative, one must begin with the electron itself. Every free electron carries an intrinsic quantum property called spin, which in a magnetic field can orient only parallel or antiparallel to the field — the binary up-or-down quantization famously demonstrated by Otto Stern and Walther Gerlach more than a century ago. In an undisturbed thermal ensemble the two orientations are populated almost perfectly equally, following a Boltzmann distribution that grants only a vanishing edge to the lower-energy, parallel state. At room temperature and a field of 0.1 tesla, the authors calculate, the excess of parallel spins amounts to roughly 0.045 percent — about 448 extra parallel spins in a population of one million. That minuscule imbalance produces DPPH’s paramagnetic susceptibility of approximately 1 × 10⁻⁴ and its relative permeability of 1.0001. While magnetic resonance and quantum information science can override such statistics with resonant radiofrequency pulses, the Greek team pursued a different route entirely: reshaping the geometry of a static, direct-current magnetic field.
DPPH — 2,2-diphenyl-1-picrylhydrazyl — is a dark crystalline powder whose molecules each carry a single loosely bound unpaired electron, one per 41 atoms, so that the bulk material behaves, in the authors’ words, as a macroscopic quantum spin emulator that can be studied in open air, without the high vacuum a Stern-Gerlach beam experiment demands. Its g-factor of about 2.0036 lies so close to the free-electron value of 2.0023 that it is routinely used as a reference standard in EPR spectroscopy. The angle at the heart of the experiment falls straight out of quantum mechanics. A spin-½ angular momentum vector has magnitude √(s(s+1))ħ = √(3/4)ħ, while its measurable z-component is ħ/2; the angle between the two, cos⁻¹(1/√3), works out to 54.74 degrees — the opening angle of the precession cones traced by a spinning electron as it gyrates around an external field at the Larmor frequency, some 28 gigahertz per tesla for a free electron. That is exactly the irrational magic angle θm = arctan(√2), embedded in the geometry of the cube and exploited in magic-angle spinning. Yet, the authors note, no purely physical interpretation of why this angle governs the electron’s quantization cones has ever been offered.
The team’s answer was to build a solenoid unlike any textbook magnet. Instead of winding the coil perpendicular to the solenoid’s axis, they wound it at a constant skew angle of 54.74 degrees, over ten turns with a pitch of 2.27 centimeters along a 22.7-centimeter length, guided by a 3D-printed winding jig. The skew is decisive: the current acquires a circling component, which generates the usual axial field Bz, and a second component running parallel to the axis, which produces an azimuthal, circular field BΦ around the central line. Their ratio follows tan(θm) = BΦ/Bz = √2 ≈ 1.41, so the flux lines twist down the bore in a helix pitched at the magic angle — the same principle used to confine plasma in nuclear fusion stellarators. To concentrate the field, the coil was wound on a 28-centimeter MnZn ferrite rod, 10.2 millimeters in diameter, whose effective relative permeability of about 154 was determined from a 7-microhenry inductance reading taken with an RLC bridge; the device was driven by a 30-volt supply through a 6-ohm current-limiting resistor. A hemispherical cavity, five millimeters across and 2.5 millimeters deep, was CNC-drilled at the rod’s center and sized to hold precisely 36 milligrams of DPPH powder.
Over a six-month campaign the researchers recorded more than 300 field measurements with an Extech MF-100 Hall-effect magnetometer, each point averaged over five experimental runs and carrying a statistical error of ±50 microtesla. Three configurations were compared: the probe pressed against the bare ferrite, the probe in the empty cavity, and the probe in the cavity filled with DPPH. The decisive contrast came from the last two. With the cavity empty, the local field measured 2.5 millitesla at one representative drive current; packed with DPPH, it read 4.2 millitesla. Theory predicts the powder’s own magnetization should have contributed a mere 0.227 microtesla to that field. Instead, the difference between the two readings — 1.7 millitesla — exceeded the prediction by a factor of roughly 7,488. Across the full range of drive currents, the measured anomaly averaged about 6,320 times the expected paramagnetic response, and the inferred relative permeability of the exposed powder climbed to approximately 1.4 — a value the authors classify as weakly ferromagnetic. In a conventional solenoid, the air and DPPH traces should lie tangent to one another; nothing of the kind was seen.
Stranger still, the effect outlived the field that created it. After the power was disconnected, the team emptied the powder from the cavity and observed it being pulled toward a grade-N42 neodymium permanent magnet — mainly the lighter flakes — a full hour after exposure. The treated sample also yielded a hysteresis loop characteristic of ferromagnetism, with a remanent magnetic moment of 0.625 emu, equivalent to 0.625 × 10⁻³ A·m² in SI units, and a saturation moment of 1.8 emu corresponding to a flux density of about 62.83 millitesla — values the authors note sit roughly five orders of magnitude above the predicted spontaneous moments of the untreated paramagnet. Perspective matters: a relative permeability of 1.4 remains far below iron’s typical value near 1,000, and the authors describe the transformation as a soft ferromagnetic transition rather than a dramatic one. But by the standards of paramagnetism — where any permeability above 1.0001 would be remarkable — the shift is enormous, and it reproduced consistently across repeats spanning half a year.
Because extraordinary claims demand extraordinary controls, the team rebuilt the experiment with one crucial change: a second solenoid wound in the normal horizontal fashion, with four turns over five centimeters, the same ferrite material and cross-section, the same CNC-drilled cavity, and a fresh 36-milligram sample drawn from the same one-gram batch of DPPH. There, everything behaved exactly as textbooks demand. The ferrite measurements matched theory, and the traces for the empty and DPPH-filled cavities were tangent within instrument resolution — the powder acting as a pure paramagnet with negligible magnetization. The logic of the control is pointed: if magnetic contamination from the drilling process had tainted the sample, it would have produced the same anomaly in both solenoids regardless of winding geometry. Instead, the anomaly appeared only in the magic-angle device. To close the contamination argument further, the researchers subjected the exposed powder to non-destructive X-ray fluorescence analysis, assisted by Professor Emeritus Nikolaos Kallithrakas-Kontos of the Technical University of Crete; no manganese, iron or zinc — the constituents of the ferrite — were detected at the marker energies where such impurities would be expected.
Translated into the language of spin populations, the numbers become genuinely startling. A permeability of 1.4 implies a magnetic susceptibility of 0.4, and from the measured field contribution of 1.7 millitesla the team derives a magnetization of about 1,353 amperes per meter for the sample. Complete parallel alignment of all the unpaired electrons — some 5.5 × 10¹⁹ of them in 36 milligrams — would instead yield a saturation magnetization of roughly 14,167 amperes per meter. The measured value therefore corresponds to a net excess alignment of about 9.6 percent. Working through the arithmetic, the authors conclude that the spin statistics shifted from the normal paramagnetic split of 50.022 percent parallel versus 49.978 percent antiparallel to approximately 54.8 percent parallel versus 45.2 percent antiparallel. Measured against the tiny Boltzmann excess of about 0.045 percentage points, that is a roughly 213-fold amplification of net spin polarization — achieved, if the interpretation holds, without a single radiofrequency pulse, at room temperature, in open air.
The proposed mechanism is where the paper ventures onto speculative ground, and the authors are candid about it. They suggest the effect is a kind of spatial geometric resonance: a helical external field pitched at 54.74 degrees may couple to an intrinsic geometric property of the electron’s charge itself, biasing the spin-alignment statistics away from the Boltzmann distribution. The hypothesis builds on the team’s earlier theoretical work, which argued that the magic angle is embedded in the charge geometry of the electron. The authors emphasize, however, that this remains a working hypothesis. DPPH powder is magnetically isotropic, the quantization axis is set by the external field, and establishing a causal link between the ferromagnetic response and the 54.7-degree pitch will require comprehensive vector-field mapping and systematic magnetometry. They also stress that the experiment probed fields only up to about 38 millitesla inside the DPPH-filled cavity, leaving open whether the effect grows linearly, saturates, or strengthens as the applied field increases.
The roadmap the authors propose for independent verification is concrete. They call for angle-sweep experiments with solenoids wound at different pitches to test whether 54.74 degrees is truly special, three-axis magnetometry inside the cavity, and trials with spin-diluted DPPH — unpaired electrons isolated in a diamagnetic host matrix — to determine whether inter-radical exchange interactions participate in the phenomenon. The most decisive test, they suggest, would be a modified Stern-Gerlach experiment incorporating the magic-angle helical field inside a high-vacuum atomic beam, potentially delivering conclusive evidence. If independently confirmed, the implications could extend well beyond magnetism: controllable spin polarization underpins spintronics, quantum communication networks and quantum computing, and the authors point to possible applications in quantum entanglement research. The work was funded by DiodeBell S.A., a detector manufacturer based in Sitia, Crete. For now, the result stands as a tantalizing anomaly — a paramagnet that apparently remembers having been a magnet, summoned by nothing more than a coil of wire wound at the very angle the universe seems to have reserved for the electron itself.
Subject of Research: Induction of a ferromagnetic phase transition in the paramagnetic organic free radical DPPH by a helical magnetic field pitched at the 54.74° magic angle, and the resulting biasing of unpaired-electron spin alignment statistics toward parallel alignment.
Subject of Research: Technology and Engineering
Article Title: Ferromagnetic phase transition of DPPH induced by a helical magnetic field
Article References: Markoulakis, E., Chatzakis, J., Konstantaras, A., Vasilaki, E., Antonidakis, P., Rigakis, I., & Antonidakis, E. (2026). Ferromagnetic phase transition of DPPH induced by a helical magnetic field. Results in Physics, 88, Article 108742. https://doi.org/10.1016/j.rinp.2026.108742
Image Credits: AI Generated
DOI: 10.1016/j.rinp.2026.108742
Keywords: DPPH, ferromagnetic phase transition, magic angle, helical magnetic field, spin polarization, paramagnetism, magnetic permeability, electron paramagnetic resonance, quantum spin control, hysteresis, spintronics
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Denise Maddox. (September 3, 2026). Helical magnetic field triggers ferromagnetic phase transition in DPPH. Scienmag. https://scienmag.com/helical-magnetic-field-triggers-ferromagnetic-phase-transition-in-dpph/
Denise Maddox. “Helical magnetic field triggers ferromagnetic phase transition in DPPH.” Scienmag, 3 September 2026, https://scienmag.com/helical-magnetic-field-triggers-ferromagnetic-phase-transition-in-dpph/. Accessed 3 September 2026.
Denise Maddox. “Helical magnetic field triggers ferromagnetic phase transition in DPPH.” Scienmag. September 3, 2026. https://scienmag.com/helical-magnetic-field-triggers-ferromagnetic-phase-transition-in-dpph/
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Tags: DPPH organic radicalDPPH radicalelectron spin and magnetic propertiesferromagnetic phase transitionHelical magnetic fieldhelical solenoidhelical solenoid experimentinfluence of magnetic field orientationmagnetic field effects on organic radicalsmagnetic field orientationmagnetic permeability changemagnetic phase transitionmagnetic phase transition in powdersmagnetic resonancemagnetic resonance “magic angle”paramagnetic to ferromagnetic transformationquantum spin propertiesremanent magnetizationunconventional magnetic phenomena
