Magnetoresistance Collapse

Updated 29 July 2025

Magnetoresistance collapse is the abrupt drop in electrical resistivity driven by transitions in electronic, magnetic, structural, or topological states.
It manifests in various materials such as transition metal oxides, semiconductors, and topological insulators, leading to effects like colossal and giant magnetoresistance.
Understanding this phenomenon relies on techniques like effective medium theories, quantum transport models, and investigations into phase separation for advanced spintronic applications.

Magnetoresistance collapse refers to the abrupt and often colossal decrease of electrical resistivity in a material as a function of magnetic field, temperature, or another external variable, typically associated with sharp modifications of the electronic structure, transport scattering rates, or phase composition. This phenomenon can be driven by electronic, magnetic, structural, or topological transitions and occurs across a diverse range of systems, including transition metal oxides, semiconductors, topological materials, and engineered heterostructures. Magnetoresistance collapse underlies several prominent effects, including colossal magnetoresistance (CMR), giant magnetoresistance (GMR), negative magnetoresistance in two-dimensional systems, and anomalous resistive switching near metal-insulator transitions.

1. Fundamental Mechanisms and Theoretical Frameworks

The microscopic origins of magnetoresistance collapse are system-dependent but universally involve the underlying control of charge carrier dynamics via magnetic, structural, or electronic transitions:

Carrier Density Collapse: In manganites such as Sm₀.₅₅Sr₀.₄₅MnO₃, the CCDC model captures the collapse of resistivity across the ferromagnetic–paramagnetic transition by associating it with a sudden increase in the density of mobile polarons when localized bipolarons (bound by strong electron-phonon coupling) are broken by p–d exchange splitting at $T_c$ . This is mathematically modeled by a ferromagnetic volume fraction $V$ and effective medium theory for resistivity:

$\rho_{\rm eff} = \rho_{\rm ferro}^V \rho_{\rm para}^{1-V}$

with specific forms for each phase (1105.2507).

Quantum Transport and Fermi Surface Segmentation: In compensated metals such as Cr, Mo, and W, low-temperature colossal MR anomalies are governed by quantum transport across sharp Fermi surface arcs induced by interactions such as SDW order, even when full cyclotron orbits are not realized (Feng et al., 22 Jan 2025). Open orbits and near-perfect electron-hole compensation result in non-saturating and exceedingly large MR.
Magnetically Driven Metal-Insulator Transitions: In systems including Ti-doped Ca₃Ru₂O₇ and EuSe₂, application of moderate magnetic fields induces metamagnetic transitions (e.g., AFM-to-FM) that close the electronic bandgap, driving an insulator-to-metal transition and CMR exceeding $10^{14}\%$ (Dong et al., 23 Dec 2024, Zhu et al., 2018).
Spin-Orbit and Disorder Effects: At LaAlO₃/SrTiO₃ interfaces, interplay of Rashba spin–orbit coupling and finite-range impurity scattering under magnetic field leads to the collapse of resistance due to a suppression of interband scattering channels and strong Fermi surface anisotropy (Diez et al., 2014). Similar effects from broken spin helicity in strong spin–orbit systems (e.g., Bi₂Te₃) cause a large, quasi-linear magnetoresistance, modeled by

$R(B)/R(0) = \frac{1+4x^2}{1+x^2}$

with $x = (g\mu_B B)/(\alpha k_F)$ (Leusink et al., 2014).

Quantum Criticality and Strange Metals: In strongly correlated metals near quantum critical points, magnetoresistance collapse is explained by $B$ -linear MR and $T$ -linear resistivity arising from Planckian dissipation at "hot spots" on the Fermi surface, modeled via disorder-coupled Yukawa interactions with critical bosons:

$\rho(B,T) = \frac{\tilde{m}_f}{n_c e^2} \left[\alpha k_B T + \sqrt{(\tilde{\mu}_B B)^2 + \gamma^2 (k_B T)^2}\right]$

capturing scaling collapse observed in experiments (Kim et al., 1 Apr 2025).

2. Role of Phase Separation and Macroscopic Inhomogeneity

Intrinsic/Extrinsic Phase Separation: Magnetoresistance collapse is often amplified or broadened by spatial inhomogeneity and phase coexistence. In manganites, first-order transitions between ferromagnetic metal and paramagnetic insulator phases result in broad, disorder-broadened transitions and large MR via percolation or effective medium averaging (1105.2507). In resistive switching manganites (LSMO), electrically induced phase separation (FM regions separated by PM barriers) produces amplified and sign-reversed MR effects as a function of switching state (Salev et al., 2023).
Domain and Domain Wall Effects: In thin films with complex domain structures (e.g., Fe₁₋ₓGaₓ), competition between anisotropic magnetoresistance (AMR) and domain wall magnetoresistance (DWMR) can produce geometry- and temperature-dependent sign changes (collapse) of the MR response due to differing volume fractions and distinct temperature dependences of AMR and DWMR (Pianciola et al., 2020).
Magnetic Hysteresis and Elastic Strain: In pressure-induced transitions (e.g., MnGe), macroscopic hysteresis and phase coexistence between high-spin and low-spin states, stabilized by long-range elastic strains from magnetovolume coupling, enable extended metastable regions and abrupt, hysteretic changes in MR across transition pressures (Martin et al., 2016).

3. Experimental Probes and Phenomenology

Collapse at Well-Defined External Fields: Magnetoresistance collapse is typically triggered at critical magnetic fields associated with metamagnetic transitions (e.g., field-induced AFM-FM in EuSe₂ at $B_c = 2.1$ T for $B\parallel c$ (Dong et al., 23 Dec 2024), or at $H_3 \sim 5$ T in Mn₃Si₂Te₆ (Zhang et al., 2 Dec 2024)). The resulting drop in resistivity may span orders of magnitude (e.g., reductions by 70% or more at LAO/STO interfaces (Diez et al., 2014), or to as little as $0.1\rho_0$ in GaAs/AlGaAs quantum wells (Shi et al., 2014)).
Oscillatory and Nonlinear Response: MIRO collapse in high-mobility 2D electron systems occurs through phase-controlled interference between multiple microwave excitations, where destructive interference ( $\delta = \pi$ ) eliminates additional radiation-driven displacement of electronic orbits, suppressing resistance oscillations (1105.3592).
Thermal Bistability and Hysteresis: In quantum wells doped with Mn, bistable resistance states arise due to both magnetic (spin anisotropy barriers) and thermal (overheating) effects, with abrupt and hysteretic MR jumps possible under appropriate bias or field protocols (1106.5832).

4. Theoretical and Modeling Advances

Boltzmann Transport and Effective Medium Theories: Modeling approaches rely on mixing phase-specific conductivities via effective medium theories (1105.2507), incorporating anisotropic impurity scattering and Fermi surface topology (Diez et al., 2014), and semiclassical Boltzmann descriptions with full inclusion of finite-range disorder.
Quantum Geometric Corrections: Magnetoresistance collapse can also reflect the impact of intra-scattering quantum geometry, as in the corrective roles of Berry curvature, orbital magnetic moment, and shift vector in Bloch systems. These intra-scattering contributions, being independent of the relaxation time, can even reverse the sign of linear MR and break Kohler's rule, leading to unexpected collapse regimes (Xiao et al., 2015).
First-Principles Calculations: Band structure calculations (density functional theory) complement experimental studies showing that AFM–FM transitions in materials like EuSe₂ and Mn $_3$ Si $_2$ Te $_6$ are accompanied by field-induced bandgap closure, with Brillouin function fits used to describe field-dependent magnetization and MR collapse (Dong et al., 23 Dec 2024, Zhang et al., 2 Dec 2024).

5. Materials Systems and Case Studies

System/Class	Collapse Mechanism(s)	Key Observables
Sm $_{0.55}$ Sr $_{0.45}$ MnO $_3$ (manganite)	Polaron–bipolaron transitions, phase separation	Colossal change in resistivity at $T_c$ ; entropy anomaly
LAO/STO interface	Rashba SOC, finite-range disorder, Zeeman-induced band deformation	Giant negative MR ( $\sim$ 70%), gate/temperature modulation
EuSe₂ (AFM semiconductor)	AFM–FM metamagnetic transition, bandgap closure	MR $>10^{14}\%$ , AMR sign/angle sensitivity
Bi $_2$ Te $_3$ (topological insulator)	Helical spin-momentum locking collapse via Zeeman field	Quasi-linear MR, factor of 4 MR increase
Fe $_{0.8}$ Ga $_{0.2}$ (thin film)	AMR vs. DWMR contribution, temperature and geometry effects	MR sign change (collapse) with geometry/temp
Cr, Mo, W (good metals)	Fermi surface arcs, quantum vs. semiclassical transport	Unsaturated, anomalous MR anomalies
Quantum wells with Mn	Magnetic/thermal bistability, anisotropy barriers	Hysteretic, abrupt MR jumps under field/bias

6. Practical Implications and Applications

Spintronic Devices: Magnetoresistance collapse facilitates tunable high/low resistance states in sensors and memory elements, especially when coupled with phase separation or bistability (temperature, voltage, field control).
Nanoantenna and Sensing: Interference-driven collapse of MIRO in 2DEGs enables design of microwave nanoantennas or frequency-selective sensors (1105.3592); phase-separated structures in LSMO provide opportunities for electrically actuated switching (Salev et al., 2023).
Fundamental Probes of Phase Transitions: MR collapse serves as a sensitive probe of first-order transitions (e.g., AFM–FM switching, Mott insulator collapse), Fermi surface reconstruction, and topological transitions, extracting information on carrier scattering, phase composition, and energy landscape.
Limits to Device Performance: Understanding collapse mechanisms is essential for robust GMR devices, where collapse due to interface impurities or misalignment degrades sensor performance (Chang et al., 2014).

7. Directions for Future Study

Key avenues include the exploration of quantum geometric origins for MR collapse in broader classes of topological and correlated systems, clarification of the role of Fermi surface segmentation and open orbits in good metals, extension of phase-separated models to engineered heterostructures, and development of comprehensive frameworks linking MR collapse to quantum critical transport and Planckian dissipation (Kim et al., 1 Apr 2025).

Further, the integration of advanced computational models—incorporating thermal, electronic, magnetic, and phase separation effects—will be critical for predictive design of materials and devices that exploit or mitigate magnetoresistance collapse. Open questions involve the universal scaling properties near MR collapse, the interplay between microscopic disorder and collective phase transitions, and the limits imposed by quantum coherence and topological protection.

Magnetoresistance collapse is thus a multifaceted phenomenon governed by a network of electronic, magnetic, structural, and topological mechanisms. Its paper continues to illuminate the interplay between charge dynamics, phase transitions, and disorder, with relevance for both fundamental physics and next-generation device technologies.