Magnetic Properties of NH$_4$H$_2$PO$_4$ and KH$_2$PO$_4$: Emergence of Multiferroic Salts

Lei Meng; Chen He; Wei Ji; Fei Yen

doi:10.1021/acs.jpclett.0c02634

paper

Magnetic Properties of NH $_{4}$ H $_{2}$ PO $_{4}$ and KH $_{2}$ PO $_{4}$ : Emergence of Multiferroic Salts

arXiv:2405.09064 · doi:10.1021/acs.jpclett.0c02634

Abstract

We observe sharp step-down discontinuities in the magnetic susceptibility of NH $_{4}$ H $_{2}$ PO $_{4}$ and NH $_{4}$ H $_{2}$ PO $_{4}$ - $d$ $_{60}$ (60% deuterated) along the $a$ and $c$ -axes occurring exactly at their antiferroelectric transition temperatures. For the case of KH $_{2}$ PO $_{4}$ , less pronounced discontinuities occur at the ferroelectric transition temperature. To explain this, we treat the acid protons as individual oscillators that generate current elements which translate to magnetic forces in near resonance with each other. With decreasing temperature, the resonant forces become more commensurate which amplifies a disproportionate drop off of two types of magnetic forces to eventually trigger the structural phase transitions. For the case of NH $_{4}$ H $_{2}$ PO $_{4}$ , the associated internal magnetic field appears to aid the NH $_{4}$ $^{+}$ to order at higher temperature. At 49 K, a shoulder-like anomaly in both NH $_{4}$ H $_{2}$ PO $_{4}$ and KH $_{2}$ PO $_{4}$ is attributed to a possible onset of macroscopic quantum tunneling of protons. Our findings bring forth a new category of intrinsic multiferroic systems.

14 pages with 5 figures

Magnetic Properties of NH $_{4}$ H $_{2}$ PO $_{4}$ and KH $_{2}$ PO $_{4}$ : Emergence of Multiferroic Salts

Abstract

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Cited by in corpus (4)

Magnetic Properties of NH4​H2​PO4​ and KH2​PO4​: Emergence of Multiferroic Salts

Abstract

References in corpus (2)

Cited by in corpus (4)

Magnetic Properties of NH $_{4}$ H $_{2}$ PO $_{4}$ and KH $_{2}$ PO $_{4}$ : Emergence of Multiferroic Salts