Rare Earth's Hidden Tradeoff: New Study Finds the Strongest Magnet Isn't Always the Best Magnet

Highlights

• Simulation-based study compared NdFeB and samarium-cobalt magnets across temperatures from 25°C to 120°C and currents up to 800 amps
• N-52M NdFeB magnets produced up to 30% more torque under normal conditions but lost roughly one-third of magnetic capability under extreme heat and high current
• SmCo magnets proved far more resistant to demagnetization at elevated temperatures, potentially making them cost-effective for aerospace, military, and industrial applications
• Heavy-rare-earth-enhanced N-48SH magnets occupied a middle ground, offering improved durability over standard NdFeB at higher material cost
• Future rare earth demand may hinge on durability and operating environment, elevating strategic importance of samarium, dysprosium, and terbium alongside neodymium

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A new study (opens in a new tab) led by Haojie Fang and Professor Anjian Pan of Hangzhou Dianzi University (opens in a new tab), in collaboration with Hangzhou Permanent Magnet Group (opens in a new tab), tackles a question at the heart of the global electrification revolution: which rare earth magnets perform best inside the motors powering electric vehicles, wind turbines, industrial robots, and advanced manufacturing equipment? The answer is more complicated than many investors might assume. While high-performance neodymium-iron-boron (NdFeB) magnets delivered the highest torque and strongest performance under normal operating conditions, samarium-cobalt (SmCo) magnets proved far more resistant to heat and demagnetization under extreme conditions. The findings highlight an increasingly important reality for the rare earth industry: future demand may be driven not only by magnetic strength, but also by durability, operating environment, and supply-chain resilience.

The Battle Inside Every Electric Motor

Modern permanent magnet synchronous motors (PMSMs) are everywhere. They propel electric vehicles, spin industrial robots, drive wind turbines, power drones, and increasingly sit at the center of modern industrial economies. Most rely on rare earth permanent magnets. The dominant technology is NdFeB, which contains neodymium and praseodymium (NdPr). Higher-performance grades often incorporate dysprosium and terbium to improve resistance to heat and demagnetization.

But there is a catch.

The strongest magnet at room temperature is not necessarily the best magnet when temperatures soar and electrical loads spike.

That is the central question explored by the Chinese research team.

Simulating the Future of Motor Design

Using advanced finite-element modeling based on a motor architecture similar to that found in Tesla's Model 3, the researchers compared three commercially relevant magnets:

• N-52M NdFeB magnet
• N-48SH NdFeB magnet enhanced with heavy rare earth elements
• SmCo-28H samarium-cobalt magnet

The team tested performance at temperatures ranging from 25°C to 120°C and currents from 100 to 800 amps. They evaluated torque production, magnetic-field behavior, demagnetization risk, harmonic performance, and economic efficiency.

When Raw Power Wins—and When It Doesn't

Under normal operating conditions, the results were decisive. The N-52M magnet produced the highest torque, generating roughly 30% more torque than the SmCo motor in some scenarios. Its stronger magnetic field translated directly into greater motor performance. However, the advantage disappeared as conditions became harsher.

At elevated temperatures and high current loads, the N-52M magnet experienced significant demagnetization. In some simulated conditions, roughly one-third of its magnetic capability was lost. Motor torque flattened and performance deteriorated.

The SmCo magnet told a different story. Although weaker at room temperature, it retained its magnetic properties under extreme operating conditions and ultimately delivered superior performance in high-temperature environments. The heavy-rare-earth-enhanced N-48SH occupied a middle ground, offering better durability than N-52M but at a higher material cost.

Why Investors Should Care

The implications extend well beyond motor engineering. The study reinforces why the rare earth market is not a single commodity story. Demand depends on performance requirements. Applications prioritizing maximum power density may continue favoring NdPr-rich magnets. High-temperature applications such as aerospace systems, military equipment, advanced robotics, and certain industrial motors may increasingly favor magnets requiring samarium, dysprosium, or terbium.

This distinction matters because heavy rare earth elements remain among the most strategically constrained materials in the global supply chain. In short, the future magnet market may be defined as much by reliability as by raw magnetic strength.

Important Caveats

Investors should interpret the findings carefully. The study was entirely simulation-based and did not include physical motor testing. The authors acknowledge that experimental validation remains future work. The economic analysis also relied on pricing provided by a collaborating magnet manufacturer, which may not reflect global market conditions. Finally, real-world motors involve cooling systems, operating cycles, manufacturing tolerances, and engineering tradeoffs that were simplified in the model.

Perhaps most importantly, the study's conclusion that SmCo becomes the most cost-effective option under extreme conditions depends on the specific assumptions used in the simulation. Whether that finding holds across commercial applications remains an open question.

The Rare Earth Exchanges™ Take

For years, the industry has focused on producing stronger magnets.

This study suggests the next competitive frontier may be producing magnets that remain strong when conditions become difficult. That distinction matters.

As electrification expands into defense systems, robotics, autonomous platforms, industrial automation, and next-generation transportation, engineers may increasingly prioritize durability over peak performance.

For rare earth investors, that means future winners may not simply be the companies producing more NdPr. They may be the companies capable of supplying the entire spectrum of critical magnetic materials—including samarium, dysprosium, and terbium—needed for a world that demands both power and resilience.

Citation: Fang H., Yao Y., Pan A., Zhao L., Fan J., Yu J., Sun X., Li B., Zhang X. The Effects of the Permanent Magnet on the Performance of a Permanent Magnet Synchronous Motor Under Various Operating Conditions. Electronics. 2026;15(11):2300.