INSIGHTS | PERSPECTIVES
sciencemag.org SCIENCEYb3+ ion provided an anisotropic magneto-
striction that induced a mechanical strain
that in turn modified the polarization by
changing the dipole configuration. The
design seems simple but was powerful
enough to induce a strong magnetoelectric
coupling at room temperature. Instead of
searching in the single-phase multiferroic
family, the authors demonstrated magne-
toelectric coupling in a paramagnetic fer-
roelectric crystal, expanding the pool of
potential materials choices. The Yb3+ ion
simultaneously responded to the magnetic
field through a magnetostriction effect and
accounts for the modification of polariza-
tion through the spin-lattice coupling,
which overcame the aforementioned in-
trinsic problem in single-phase inorganic
multiferroic materials.
The work of Long et al. provides an al-
ternative strategy to realize magnetic field
control of polarization at room tempera-
ture in molecular ferroelectrics, which re-
moves the strict criterion that is typically
required of inorganic multiferroic mate-
rials. Many different molecular materials
can be designed, so this finding should also
stimulate other research directions. For
example, the inverse effect of electric-field
control of magnetization has also been
studied in inorganic materials ( 7 , 8 ).
Spintronics, in which the central theme
is the manipulation of both the charge and
spin degrees of freedom, resembles magne-
toelectric coupling. The material developed
by Long et al. is a single-molecule magnet
( 9 ). Such a material, which typically would
have weak spin scattering as well as long
spin lifetime in comparison to inorganic
counterp arts, could be an interesting build-
ing block for molecular spintronics. Spins
can be manipulated at small size with low
energy and encode computational informa-
tion. These additional degrees of freedom
offer unprecedented opportunities to de-
velop entirely new devices. One of the most
attractive ideas is to write the data electri-
cally and access them magnetically ( 10 ),
which would overcome the problems of the
large writing field of magnetic and the low
reading speed of ferroelectric random-ac-
cess memory. These effects could be used to
develop energy-efficient multibit memory,
neuromorphic computing, and logic gates
that may push device performance beyond
current limits. jREFERENCES AND NOTES- J. Long et al., Science 367 , 671 (2020).
- S. W. Cheong, M. Mostovoy, Nat. Mater. 6 , 13 (2007).
- C. Lu, W. Hu, Y. Tian, T. Wu, Appl. Phys. Rev. 2 , 021304
(2015). - J. F. Scott, R. Blinc, J. Phys. Condens. Matter 23 , 113202
(2011). - C. A. F. Vaz, J. Hoffman, C. H. Ahn, R. Ramesh, Adv. Mater.
22 , 2900 (2010). - S.-T. Han, Y. Zhou, V. A. L. Roy, Adv. Mater. 25 , 5425 (2013).
- P. Wadley et al., Science 351 , 587 (2016).
- Y. Yamada et al., Science 332 , 1065 (2011).
- L. Bogani, W. Wernsdorfer, Nat. Mater. 7 , 179 (2008).
- L. Zhou et al., Small 14 , 1703126 (2018).
ACKNOWLEDGMENTS
The authors acknowledge support from the Natural Science
Foundation of China (grant no. 61974093), Guangdong
Province Special Support Plan for High-Level Talents (grant
no. 2017TQ04X082), Guangdong Provincial Department
of Science and Technology (grant no. 2018B030306028),
and the Science and Technology Innovation Commission
of Shenzhen (grant nos. JCYJ20180507182042530 and
JCYJ20180507182000722).10.1126/science.aba6642–+ –+PEMHDipole–+ –+PHDipoleZn2+ Zn2+Electron spinME
??Electron spinFerroic properties
In these materials, polarization P or magnetization
M are intrinsic and switch only if a strong enough
feld is applied.
Multiferroic properties
In these materials, spins and dipoles couple so that
magnetic felds can align dipoles, and electric felds
can align spins.
Magnetic-feld control
Long et al. made a compound that couples Yb3+ spins
and Zn2+ dipoles that enables magnetic-feld control of
ferroelectricity at room temperature.
Electrical-feld control
Similar control of the magnetization with an electric
feld was not observed. Such e.ects are of interest for
electronic memories.
Ferroelectricity
In ferroelectrics, an applied electric feld E aligns
dipoles and results in a polarization P.
Ferromagnetism
In ferromagnets, an applied magnetic feld H aligns
electron spins and results in a magnetization M.
GRPAHIC: C. BICKEL/SCIENCEINFECTIOUS DISEASEIn the heat
of the night
An ancestral receptor plays a
key role in host detection by
malaria-carrying mosquitoes
By Claudio R. LazzariV
ector-borne diseases, such as malaria
caused by Plasmodium parasites
transmitted by female Anopheles
gambiae mosquitoes, are among the
most devastating and also difficult
to control problems in public health.
Considerable efforts and resources are de-
voted to the search for effective ways to limit
their transmission. An important aspect of
these efforts is unravelling the biological
mechanisms by which vectors find human
hosts. How vectors acquire and make use of
sensory information for locating potential
blood sources represents a key piece of the
mechanism, especially because the vector-
host encounter is when pathogen infection
occurs. On page 681 of this issue, Greppi et
al. ( 1 ) identify the ionotropic receptor IR21a
gene, which is conserved throughout in-
sects, as a key mediator of heat seeking in
mosquitoes carrying malaria parasites.
Mosquitoes are an important group of
disease vectors. They transmit a diversity of
pathogens, including viruses, bacteria, pro-
tozoans, and nematodes; they are present in
most regions of the Earth; and the pathogens
they transmit cause a substantial disease bur-
den. Among these diseases, malaria claims
hundreds of thousands of lives every year
globally. According to the World Health Or-
ganization, in 2017 nearly half of the world’s
population was at risk of malaria ( 2 ); there
were 219 million cases, and the estimated
number of malaria deaths was 435,000. Chil-
dren under 5 years of age are the most vulner-
able to malaria parasite infection, accounting
for 61% of all malaria deaths worldwide ( 2 ).
Even though regions of Southeast Asia, East-
ern Mediterranean, Western Pacific, and the
Americas are also at risk, the continent of
Africa has a disproportionately high share of
the global malaria burden. Malaria has even
influenced human evolution: The high mor-
tality and widespread distribution of malariaInstitut de Recherche sur la Biologie de l’Insecte, UMR 7261
CNRS–University of Tours, Parc Grandmont, 37200 Tours,
France. Email: [email protected]628 7 FEBRUARY 2020 • VOL 367 ISSUE 6478
Molecular magnetoelectrics
Magnetoelectric effects can allow magnetic
properties to be controlled by electric fields and
electrical properties by magnetic fields. The
latter was demonstrated by Long et al. for a crystal
of a compound containing a rare-earth metal,
ytterbium (Yb), and zinc (Zn) cations.
Published by AAAS