LK-99: A Leap or a Fad?

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Issue 1, Volume 114

By Lenny Metlitsky 

Twitter doesn’t usually get excited over gray blocks of metal, but it made an exception for LK-99. When Sukbae Lee and Ji-Hoon Kim, a research duo from Korea University, announced their discovery of the new room-temperature ambient pressure superconductor in late July, the internet was, you could say, levitating with enthusiasm. Previously-discovered superconductors, or materials that can have zero electrical resistance, have to operate at temperatures far below freezing and require lots of cooling to do so. Nevertheless, LK-99 would theoretically not require any refrigeration. Such a superconductor, if readily available, could revolutionize everything from transportation to energy efficiency to medicine; the possibilities for a material that can conduct electricity without any resistance, heat, or waste are seemingly endless. Despite these idealistic expectations, LK-99 was not able to live up to the original paper’s promise when its findings were tested in labs around the world. 

After the two researchers published the paper that detailed their supposed breakthrough, labs all across China, the United States, and Europe raced to synthesize LK-99 and put the paper’s Nobel-prize-winning level claims to the test. Many scientists were immediately skeptical of the paper because it was not peer-reviewed, so research labs across the globe began to synthesize LK-99, test its properties, and publish their results. Across many different tests performed by many different labs, LK-99 didn’t show any signs of being a superconductor. 

As the temperature is continuously lowered, superconductors display a clear distinction from other materials—they reach a point of superconductivity, at which electrical resistance (a given material's ability to stop a charge) suddenly drops off completely and becomes zero. The temperature at which this occurs is extremely low—far closer to absolute zero than any temperature naturally occurring on Earth. Early superconductors, such as the one that helped Dutch physicist Heike Kamerlingh Onnes discover superconductivity in 1911, required temperatures around 4.2 K, or −268.95 °C, for superconductivity to occur. Today, superconductors are referred to as high-temperature if they can achieve superconductivity above a temperature of 30 K (−243.15 °C). However, this label is rather misleading, as those temperatures are still far below any naturally occurring on Earth and require liquid nitrogen or liquid helium cooling. Currently, some superconductors can exist at higher temperatures—even approaching room temperature—but only at hundreds of gigapascals of pressure. Even with these limitations, superconductors have proven to be extremely useful. Superconductors have been used to create superconducting magnets, which produce strong magnetic fields more cheaply and efficiently than even the strongest magnets. The applications of strong magnetic fields are plentiful, but the most common ones are levitation, frictionless movement, and imaging technology; superconductors are used by MRI machines to generate strong magnetic fields, and they’re also used to provide frictionless levitation for Magnetic Levitation (Maglev) trains in Japan.

If LK-99 had been a true room-temperature superconductor, it could have been used for a wide variety of other applications due to the possibility of it functioning at higher temperatures and lower pressures. It could’ve produced an eco-friendly power grid that wouldn’t waste the energy lost today and (literally and figuratively) provide no resistance for ultra-long-distance energy transport, thereby making it easier to fight climate change. Additionally, it could have improved transistor technology by at least a few orders of magnitude, inducing a massive spike in computing power, all while being the cheapest option on the market. 

However, LK-99’s structure was decisively proven to make superconductivity impossible by two teams—the sharp resistivity never drops to zero as its temperature is lowered. The unexpected “levitation” detailed in the original paper and recorded in a viral Twitter video could be explained by a phenomenon called ferromagnetism, or an alignment of electron spin that allows for permanent magnetic fields. On top of superconductivity and levitation claims being debunked, LK-99 actually turned out to be the exact opposite of a superconductor: an excellent insulator with extremely high resistance (in the millions of ohms) and ferromagnetic qualities. 

LK-99 didn’t turn out to be the grand technological leap that scientists were hoping for, but it did demonstrate the strengths and weaknesses of the scientific community. On one hand, it showed the gullibility of the scientific world and general public when faced with unproven claims that haven’t been peer-reviewed. On the other, it showed that the combined knowledge of the international network of researchers and scientists is capable of fact-checking and discrediting any potentially dubious claims. The initial excitement around LK-99 indicates that science still has the power to amaze a wide variety of people, from seasoned researchers to those intrigued by revolutionary breakthroughs. We have learned that, currently, material science has not reached the point of such a technological breakthrough in superconductor technology. It is possible that we will one day discover a room-temperature superconductor; it just won’t be LK-99.